Stampaggio a iniezione di acetale

Stampaggio ad iniezione di acetale

Acetal injection molding O Stampaggio a iniezione POM parts manufacturered from Polyoxymethylene (POM), a highly processed thermoplastic material. POM can take a homopolymer or copolymer acetal form. Homopolymer acetal exhibits high strength because of its crystalline structure. However, it can be problematic as a result of the highly specific melting point. Copolymer acetal is easier to mold due to the larger processing window. It is less mechanically strong than the previous material as its crystalline structure is less ordered.

Some renowned suppliers offer copolymer acetals. While DuPont, a well-reputed material provider offers only Delrin®, a homopolymer with enhanced properties. Delrin® grades are categorized according to their strength, stiffness, viscosity, and resistance. It is compatible with both injection molding and CNC machining. Acetal mold products/parts are vitally used in automotive, medical as well as fluid handling sectors.

This article primarily focuses on acetal plastic injection molding, POM properties, benefits, and design guidelines for fabricating parts from POM. Moreover, we will provide an Injection Molding Design Guide, certain suggestions, and recommendations for optimal outcomes for your acetal injection molding project.

Acetal injection molding

What Is Acetal?

Acetal, which is also known as polyoxymethylene (POM), is a tough and high-performance thermoplastic. It’s a semi-crystalline material, commonly used for engineering applications. Acetal polymers are formed by the linking of long chains of the molecular formula CH2O. Some copolymer monomers are also incorporated to provide additional functionality. Depending on the structure, acetal can be a homopolymer or copolymer in nature depending upon the structure.

The best-known homopolymer acetal is DuPont™ Delrin®. Acetal plastics have a high strength and stiffness which make them ideal for applications that require high strength but low flexing. These plastics also possess low friction and high wear rates. Low water absorbency makes acetal possess excellent resistance to dimensional changes. For these reasons, acetal is used in place of metals for many uses.

Acetal/POM Material Properties

Table: Properties of various acetal grades

Proprietà Delrin® 100 BK602 Duracon® M90-44 Celcon® M90 Kepital® F20-03 Hostaform® C9021
Physical
Densità (g/cm³) 1.42 1.41 1.41 1.41 1.41
Shrinkage Rate (%) 1.9–2.2 2.1–2.3 1.9–2.2 2.0 1.8–2.0
Rockwell Hardness 120 R 80 M NA NA NA
Mechanical
Resistenza alla trazione (MPa) 72 62 66 65 64
Elongation at Yield (%) 23 35 10 10 9
Modulo di flessione (GPa) 2.9 2.5 2.55 2.55 NA
Resistenza alla flessione (MPa) NA 87 NA 87 NA
Stampaggio a iniezione
Drying Temperature (°C) 80–100 NA 80–100 80–100 120–140
Drying Time (hrs) 2–4 NA 3 3–4 3–4
Melt Temperature (°C) 215 200 205 180–210 190–210
Mold Temperature (°C) 80–100 80 90 60–80 85

The table above presents the POM trade names mentioned above together with their properties. Homopolymer Delrin® 100 has the highest tensile strength because of a higher degree of crystallinity in the polymer. POM is characterized by very good tensile and flexural strength but by a high rate of shrinkage. Depending on the application requirements certain POM grades may contain fillers to improve strength, corrosion, or UV resistance.

Pros of POM Injection Molding

Acetal has high performance with desirable engineering characteristics. The material offers high fatigue and creep strengths when subjected to stress. High mechanical strength makes it optimal for different precision-demanding sectors, like aerospace, and automotive. Low friction helps POM to have a very small level of wearing over a long period. Moreover, acetal does not rust/corrode and can also work at high temperatures.

Resistenza alla fatica

Acetal injection molding parts has good performance characteristics when it is subjected to repetitive stress cycles. It is most appropriate in situations where the load bearing is constant such as gears. Thus, homopolymer POM provides better fatigue strength than copolymers do. These peculiar features make it possible to have long-term dependability in conditions of high stress. Strength in fatigue makes POM suitable for use in applications where mechanical parts are desired.

Creep Resistance

POM molded part exhibits dimensional stability when subjected to mechanical loads in the long term. It has a very low tendency to undergo permanent deformation, even when it is subjected to constant stress. This characteristic makes POM suitable for use in load-bearing applications. The material’s lack of creep also makes it ideal for structural applications. This is a very reliable area of the performance under pressure of POM.

High Strength

POM injection molding parts provides the best tensile and flexural characteristics. The material provides the rigidity required in high-performance mechanical parts. Homopolymer versions of POM show even greater strength as compared with the copolymers. Some common uses include conveyors and safety-related components. POM mechanical characteristics are quite versatile to allow various applications.

Low Friction

Low friction of POM decreases wear and tear in the sliding members. The material is well-suitable for use in areas where there a little movement variation involved. It requires minimal maintenance because of its natural tendency to reduce friction: This ability of POM to resist abrasion keeps the molding parts ‘ life quite long. Therefore, it is often applied where low friction is a necessity.

Food Safety

Advanced POM food-grade material meets safety standards applicable to food contact products. POM can also be used by manufacturers of food processing machinery and equipment. It has complied with the FDA, USDA, and all legal and regulatory requirements of strict safety. Due to its non-toxicity POM is well-suited to employ in these sectors. acetal injection molding part is widely used in food processing equipment for its reliability and dependability.

Stabilità dimensionale

Acetal injection molding products comprise accurate dimensions once they have cooled from the molding processes. During molding its shrinkage rate is relatively high but afterward, it remains almost uniform. Dimensional stability is important in sectors such as automotive and electronics. POM injection molding parts remain dimensionally stable during mechanical application and pressure. This characteristic is a prerequisite for precision components.

Resistenza alla corrosione

POM is relatively immune to most chemical agents such as fuels and solvents. It is best used in places that may come into contact with chemicals. For example, cylindrical storage tanks. However, the material is affected by strong acids and bases. POM stands up well to chemical attack and, therefore is the right material for use in fluid management. It also has good and stable chemical resistance as well as a long service life in harsh conditions.

Resistenza al calore

POM is capable of enduring usage in areas that have high temperatures, up to 105°C. Homopolymer grades withstand higher heat bursts than copolymers do. The intended property is crucial for those components that are exposed to varying temperature conditions. This characteristic makes POM suitable for use in industries because of its tolerance to high temperatures. The right choice of materials used means the ability to withstand thermal climates. To high temperature plastic pgae to know more high temperature materials.

POM plastic molding services

Key Considerations in POM Injection Molding Design

Injection molding acetal prefers the use of stainless steel molds. The material being used has a corrosive effect. Therefore the molds used must be strong and resistant. High shrinkage calls for a keen mold design to achieve precise parts. POM is widely applied in automotive, industrial, and medical parts. So, molding must be done in the right manner and in this case, it is going to ensure that the degree of precision and quality output is going to be high. It is important to take into account some features when designing for POM injection molding.

Wall thickness should be in the range of 0.030 and 0.125 inches. By maintaining thickness variation to the minimum, it is possible to achieve a uniform thickness of the part. The management of tolerances is crucial because the company’s rate of shrinkage is high, and this is evident from the case of POM. Radii should be minimized particularly in the regions that experience maximum stress. Draft angles ranging from 0.5 to 1 degree are ideal because their ejection is smooth.

Spessore della parete

The thickness of the wall has a direct influence on the quality of injection-molded POM parts. Thicker sections may also make the piece warp or shrink in some ways or the other and this may not be desirable. This way the overall structure is improved and one maintains consistent thickness. However, extremely thin walls though difficult must fall within certain limits. Wall thickness plays a vital role in structural applications and if well done, helps reliably to withstand high pressures.

Tolleranze

POM exhibits high shrinkage which can become a challenge when working on POM molding parts that have to be within close tolerance. In particular, thicker walls are found to increase the probability of tolerance deviation. Designing to ensure equal measurements is not a bad idea as this will ensure that dimensions are consistent. There is always a way of properly molding and this would ensure that tolerances are within the acceptable limits. Problems due to dimensional changes are well managed by planning and control.

Radii

Radii in part designs help to minimize stress concentration in the use of the part. Sharp corners are always a problem because they are the points that can cause a structure to be less durable. By including radii these high-stress areas are minimised hence increasing the life of the part. Radii must be equal to or greater than 0.25 times the nominal thickness of the pipe wall. Smaller radii reduce stress; however, larger radii, up to 75% offer better stress distribution.

Angolo di sformo

It is possible to achieve high POM part ejection with minimal draft angles. POM has a low friction, it also has the possibility of having draft angles of 0.5 degrees. It is conceivable that for parts such as gears, zero drafts may not be essential to satisfy design specifications. Drafts help to avoid the difficulty of the separation of parts from molds with minimal or no harm. Good draft design enables efficient production and better quality of the part to be produced.

POM Material Processing Challenges

What makes POM difficult to process? Well, certain determinants decide its optimal functioning. As POM has a slight or low tolerance to high thermal conditions. Several factors are taken into consideration by mold operators during injection molding. Such factors are heat control, moisture level, molding parameters, and shrinkage. These elements are important to achieve successful production of high-quality POM injection molding parts.

Calore

One of the most critical aspects to be managed in POM injection molding is heat. When heated at a temperature higher than 210°C, the material undergoes thermal degradation. This breakdown results in the formation of by-products that are corrosive and end up affecting the injection mold. Mold temperature should be between 60-100°C for the best outcome. Further, the short heating cycles are also beneficial because they do not stress the material too much. With the increase in temperature, it should be accompanied by a decrease in residence time to achieve quality.

Umidità

The moisture absorption of POM is quite low and it lies between 0.2 to 0.5%. However, it is advised that POM resin should be dried before processing to get the best results. The drying time is normally between 3 to 4 hours, depending on the POM grade. This is important so that moisture levels are low during molding to decrease the occurrence of defects. Careful preparation avoids problems related to moisture during the injections.

Molding Parameters

The right molding parameter must maintained for POM injection molding. The successful injection pressure identified is between 70 to 120 MPa to ensure good repeatability of the experiment. A medium to high injection speed is also desirable to achieve a smooth production of the part. Molded part control requires proper parameter control to ensure that the molded parts meet specific specifications. By closely tracking these parameters it is possible to enhance the quality of the final product.

Restringimento

Shrinkage is a usual problem with POM materials including Delrin®. Shrinkage rates are usually between 2 to 3.5 percent in the cooling stage of the cycle. The majority of shrinkage happens when the part is still in the mold, and the rest are during post-ejection. Non-reinforced homopolymer POM exhibits greater shrinkage than copolymer materials. These shrinkage rates must be considered in mold design to meet the desired dimensions.

STAMPAGGIO A INIEZIONE POM

Disadvantages of Acetal Injection Molding

Although acetal molding offers several benefits. It also has its limitations and drawbacks. In addition, acetal molds come with many challenges. These limitations must be carefully considered during the molding process for companies to achieve good-quality end-use products.

Poor Weather Resistance

Acetal is highly vulnerable to degradation. Normally, in situations when it’s exposed to ultraviolet light or UV light. This is so because constant exposure to them can cause major color shifts and eventually affect their performance. UV deteriorates the aesthetic value and physically weakens the material. Moreover, UV radiation strips the structure of polymers away. Hence, there must be use of stabilizers to enhance acetal’s resistance to weathering. These stabilizers may not prevent the degradation fully over long periods outdoors thus hampering the use of acetal in exterior uses.

Fragilità

In its solid state, Acetal is highly resistant and possesses high stiffness, but undergoes brittle failure under special circumstances. Temperature Low temperature affects the material characteristic of acetal and makes it prone to crack or fracture when experiencing an impact. However, this brittleness is a drawback in any applications where high-impact strength is desirable, particularly at low temperatures. There are significant challenges in designing products that are molded from acetal so that they can endure shock without fracturing.

Concerning the effects of the acetal molding process on the mechanical properties of parts, considerations should be taken into account.

Acetal Injection Mold Design

When designing an application using acetal material it is important to get the mold right because it determines the quality and stability of the end product. Here are some key design guidelines to follow:

  • Runner Diameter: The runner diameter is suggested to be between 3 and 6 mm to enable easy flow of the material during injection.
  • Gate Length: Ideally, the gate length should be some 0.5mm to provide proper regulation of the throughput of the material. It improves the uniformity of the mold so that no defects are formed when filling the mold with the material.
  • Round Gate Diameter: This should be between half and six times the thickness of the part being molded. By sizing the gates properly it eliminates cases like short shots and weld lines.
  • Rectangular Gate Width: By design, the width of the rectangular gates must measure at least twice the thickness of the product. This should ideally be about 0.6 times the wall thickness as far as the structural reinforcement of the vessel is concerned.
  • Draft Angle: A mold angle of 40 to 1 30 is proposed for straightforward removal of the molded part without any abrasion on the surface.

Pre-Drying Acetal Material

Even if it has a high moisture absorption value, the acetal part is suggested to be pre-dried before injection molding for the resin. Pre-drying also reduces the presence of some form of moisture that is destructive like the formation of voids or bubbles. The drying process should be at a temperature of 80–100°C and should take 2-4 hours. Correct drying is as important since it assists in retaining various characteristics of the materials besides facilitating guzzle-free molding.

Acetal Molding Temperature Control

When it comes to acetal injection molding it is very crucial to maintain both moisture and melt temperature for enhanced results. The mold temperature should be maintained between 75 and 120 centigrade and the melt temperature to be between 190 and 230 centigrade (374 and 446 Fahrenheit respectively). Parameters such as accurate temperature regulation also manage problems like distortion shrinkage or even poor surface finish. Accurate regulation of thermal conditions helps to cool uniformly and, therefore, minimize stresses when improving the dimensional characteristics of the final product.

Pressione di iniezione

Each material requires a specific injection pressure that needs to be attained to provide the specific part quality. The pressure range is in the range of 40–130 MPa depending on the melt flow rate of acetal and the thickness and sizes of the runner gate and part. When pressure is low, the mold can be filled inadequately, and if pressure is high, then there is likely to be flash or other defects. The optimum pressure is important for the creation of appropriate part formation and the exclusion of defects.

Injection Molding Speed

The injection speed is also another that greatly influences the process of acetal molding. Depending on puddle formation, mold injection speed ranges from moderate to fast to avoid defect creation as the mold is filled. In case of slow speed, the flow marks or surface imperfections are seen on the surface. On the other hand, high speed may lead to what is called jetting or shear overheating which is bad for the strength and surface finish of most parts. Through modification of the injection speed, one can be able to eliminate the molding defects as well as enhance the molding productivity.

These considerations allow manufacturers to enhance the efficiency of their acetal injection molded parts by controlling parameters, and issues incurred. To make the best use of the positive attributes of acetal while avoiding its drawbacks, certain aspects of mold design, material handling as well as the process must be finely tuned.

Conclusione

Acetal or polyoxymethylene is a type of injection-molded semi-crystalline thermoplastic. This material is commonly used in mechanical parts such as bushings, bearings, gears, and sprockets.

Compared to metals and other plastics acetal has a low friction coefficient and high rigidity. These features greatly improve its wear properties, and thus the resultant products are long-lasting.

Altogether these characteristics make acetal a material of choice for many engineering applications. The proper processing and design of the equipment improve their efficiency and durability in different industries.

Introducing acetal into production processes may result in higher efficiency and lower frequency of maintenance of mechanical equipment.

 

/0 Commenti/da
,

Spessore della parete dello stampaggio a iniezione, la sua importanza e fattori che lo influenzano

stampaggio a iniezione parete spessa

Lo stampaggio a iniezione è un metodo generale che viene solitamente utilizzato nell'industria manifatturiera. Qui, il materiale viene spinto ad alta pressione in una cavità dello stampo. In genere, durante la fase di progettazione, lo spessore della parete di una parte è una delle considerazioni più importanti. Quindi, in questo articolo, discuteremo dello spessore della parete, della sua relazione con lo stampaggio a iniezione e della sua comprensione di come influisce sulla qualità della parte e sulla capacità di produzione.

Come definiresti lo spessore della parete nello stampaggio a iniezione?

Stampaggio a iniezione Spessore della parete è una misura dello spessore delle pareti della parte stampata prodotta con l'ausilio di un processo di stampaggio a iniezione. È la quantità, in millimetri, da una delle superfici più esterne della parte all'altra superficie più esterna. Inoltre, lo spessore della parete è forse il più importante, in quanto determina la capacità della parte stampata di resistere ai meccanismi di guasto. Questi possono includere cedimento, deformazione, deformazione e difetti estetici. Lo spessore della parete deve sempre essere progettato per adattarsi a determinate condizioni, ovvero il materiale, il funzionamento della parte, il design e l'attrezzatura di stampaggio utilizzata. Quindi, selezionare lo spessore appropriato per le pareti è fondamentale per fornire le parti desiderate.

spessore della parete dello stampaggio a iniezione

Qual è l'importanza di uno spessore uniforme della parete?

Uno spessore uniforme della parete è molto importante quando si tratta di alta qualità. Aiuta a fornire parti stampate a iniezione prive di difetti e strutturalmente sane e aumenta anche l'integrità strutturale. Oltre a questo, aiuta a migliorare l'efficienza e ottimizzare l'uso del materiale. Quindi. Discutiamo di più sull'importanza dello spessore uniforme della parete.

1. Impatto sulla qualità delle parti

Quindi, prima di tutto, uno spessore di parete uniforme fornisce un raffreddamento costante e previene anche sollecitazioni e deformazioni interne. Oltre a questo, aiuta a mantenere dimensioni precise in modo da evitare imperfezioni superficiali, ovvero segni di depressione e deformazioni. Inoltre, aumenta sia la funzionalità che l'estetica della parte finale.

2. Riduzione dei difetti

In secondo luogo, se lo spessore della parete è uniforme, alla fine riduce deformazioni e segni di cedimento. Favorisce un raffreddamento uniforme e riduce le sollecitazioni interne, quindi alla fine ci dà parti più resistenti e durevoli con meno punti deboli.

3. Integrità strutturale

Lo spessore uniforme della parete fornisce una distribuzione equilibrata del carico per migliorare la resistenza e la durata. Inoltre, migliora le proprietà meccaniche dei prodotti, ovvero la resistenza alla trazione e all'impatto, per fornire prestazioni affidabili.

4. Migliore efficienza produttiva

Facilita inoltre la progettazione dello stampo e i processi di stampaggio a iniezione. Riduce i tempi di ciclo e i costi di produzione. Inoltre, promuove anche un raffreddamento più rapido e migliore e ottimizza il processo di produzione.

Considerazioni sui materiali nello stampaggio a iniezione

Di seguito sono riportate le considerazioni sui materiali per lo spessore della parete della fusione a iniezione.

  1. Tipo: Esempi: materiali termoplastici, tra cui ABS e PC; materiali termoindurenti come le resine epossidiche; elastomeri come la gomma siliconica; e TPE.
  2. Fluire: Il riempimento dello stampo dipende dalla viscosità, dove il prodotto deve essere sottile. Richiede materiale ad alta fluidità e, dove è richiesto lo spessore, il materiale a bassa fluidità è il più appropriato.
  3. Restringimento: Nel caso dei metalli, le loro dimensioni si riducono partendo dallo stato fuso e si passa allo stato solido o fuso; questo aspetto viene preso in considerazione nella progettazione di uno stampo per realizzare una parte della dimensione corretta.
  4. Forza e flessibilità: Altri fattori da considerare sono la rigidità e la resistenza, che determinano lo spessore del muro durante la costruzione, per ottenere un risultato strutturale affidabile.
  5. Resistenza: resistenza al calore e alle sostanze chimiche per favorire una lunga durata in qualsiasi tipo di condizione operativa.
  6. Finitura superficiale: Le caratteristiche di un materiale di stampaggio influiscono sulla finitura superficiale e sull'aspetto della parte stampata, aumentandone l'estetica e la levigatezza.
  7. Costi e impatto ambientale: Tra questi rientrano il costo unitario del materiale, la sua riciclabilità e la sua conformità agli standard di sostenibilità.

Quindi, la seguente tabella descrive gli intervalli adatti che il rispettivo materiale può supportare; di seguito è riportata una parte stampata a iniezione a parete spessa che abbiamo realizzato in materiale PC, scopri di più su Stampaggio a iniezione di PC.

Stampaggio a iniezione a parete spessa

 

Materiale Intervallo tipico di spessore della parete:
addominali 1,0–3,0 millimetri
Policarbonato (PC) 1,0–3,0 millimetri
Polipropilene (PP) 0,8 – 2,5 millimetri
Polietilene (PE) 1,0–3,0 millimetri
Poliammide (PA) 1,0–3,0 millimetri
Acetale (POM) 0,8–3,0 millimetri
Polietilene tereftalato (PET) 1,0–3,0 millimetri
Cloruro di polivinile (PVC) 1,0–3,0 millimetri
Acrilico (PMMA) 1,0–3,0 millimetri
Polietilene Vinil Acetato (EVA) 1,0–3,0 millimetri
Elastomeri termoplastici (TPE) 1,0–3,0 millimetri
Resina epossidica 1,0 – 5,0 millimetri
Silicone 1,5 – 6,0 millimetri

Linee guida per la progettazione dello spessore della parete nello stampaggio a iniezione

Ecco una breve tabella che ci aiuterà a progettare lo spessore ottimale della parete nello stampaggio a iniezione.

 

Linea guida Descrizione
Regole generali pratiche ● Mantenere uno spessore uniforme per prevenire difetti.

● Garantisce transizioni fluide e spesse.
Spessore minimo della parete ● Dipende dal flusso del materiale; i materiali ad alto flusso possono avere uno spessore di 0,5–1,5 mm.

● Assicurarsi che lo spessore minimo sia per la resistenza.

● Consentire il riempimento completo dello stampo.
Spessore massimo della parete ● Pareti più spesse (>4 mm) aumentano il tempo di raffreddamento e di ciclo.

● Ottimizzare per ridurre costi e peso.

● Le pareti più spesse rischiano di formare depressioni e vuoti.
Requisiti strutturali/funzionali ● Pareti più spesse per le parti soggette ad alto stress.

● Spessore specifico per isolamento termico ed elettrico

● Bilanciare lo spessore per flessibilità e resistenza.
Progettazione per la producibilità ● Assicurarsi della compatibilità del progetto e del flusso dei materiali.

● Includere correnti d'aria di 1-2 gradi per una facile espulsione.

● Rinforzare pareti sottili senza aggiungere volume.
Simulazione e test ● Utilizzare CAE per prevedere e risolvere i problemi.

● Prototipi di prova per convalidare il progetto.

Strumenti e risorse per l'ottimizzazione dello spessore delle pareti

Ecco alcuni strumenti e risorse che possono aiutarti ad aumentare l'efficacia dello spessore delle pareti nello stampaggio a iniezione.

Strumenti software per la simulazione

Viene utilizzato efficacemente nello stampaggio a iniezione per determinare uno spessore di parete adatto. Svolge un ruolo molto importante nella determinazione dello spessore di parete. Questi strumenti forniscono informazioni su come il materiale verrà trasportato e sul suo comportamento nel processo di stampaggio a iniezione. Quindi, i progettisti possono essere in grado di prevenire o risolvere alcune delle sfide che possono sorgere durante il processo effettivo di stampaggio. I principali vantaggi e caratteristiche includono:

  1. Analisi del flusso: Imita il processo del materiale fuso che entra nello stampo. Quindi mostra le parti in cui il materiale potrebbe finire per non fluire correttamente o dove si sta verificando la creazione di trappole d'aria.
  2. Analisi del raffreddamento: Utilizza la modellazione al computer per prevedere i modelli di raffreddamento per consentire al raffreddamento di avvenire a una velocità uniforme. Quindi, aiuta a eliminare problemi come deformazioni e segni di ritiro.
  3. Analisi dello stress: Controllare le sollecitazioni nella parte per confermare lo spessore della parete. Controlla se è ottimale e se il livello di sollecitazione è sufficiente per l'applicazione prevista ma non troppo alto.
  4. Algoritmi di ottimizzazione: Proporre modifiche da apportare allo spessore della parete e a qualsiasi altra caratteristica di progettazione. Perché può influire sulla capacità di produrre la parte e sull'efficienza del suo funzionamento.

Alcuni dei più noti programmi software di simulazione per lo stampaggio a iniezione sono Auto Desk Mold Flow, Solid Work Plastics e Moldex3D. Tutti assistono i progettisti nella progettazione di sezioni per ottimizzare le soluzioni senza difetti.

2. Opzioni di prototipazione

Esistono diversi tipi possibili di prototipazione. Ciò significa che i progettisti possono apportare importanti modifiche fisiche e formative reali rispetto ai modelli simulati. Oltre a ciò, queste opzioni mirano a produrre la parte, quindi questi metodi di prototipazione includono:

  • Stampa 3D (produzione additiva): Consente lo sviluppo di prototipi a velocità più elevate mantenendo diversi spessori delle pareti laterali. Il vantaggio più evidente è che è poco costoso testare rapidamente vari design. Oltre a questo, può essere un prototipe di forma o di funzione.
  • Lavorazione CNC: Offre prototipi contemplativi che hanno utilizzato materiali di produzione in modo che il risultato sia quasi perfetto. Questo metodo consente l'identificazione delle caratteristiche della parte meccanica e del suo comportamento in condizioni operative reali.
  • Utensili morbidi: Ciò è caratterizzato dall'uso di stampi a bassa resistenza e di breve formatura per produrre poche parti rispetto alla pressofusione. Quindi, questo approccio è vantaggioso nella valutazione del processo di stampaggio e nell'identificazione dello spessore della parete. Aiuta anche con la standardizzazione dell'intero tipo di stampo.

Quali fattori influiscono sullo spessore delle pareti nello stampaggio a iniezione?

Diversi fattori possono influenzare lo spessore della parete nello stampaggio a iniezione. Discutiamo questi fattori in dettaglio:

1. Proprietà del materiale

Queste proprietà possono includere:

  • Viscosità: Se parliamo di materiali a bassa viscosità, scorrono facilmente in sezioni sottili e consentono pareti più sottili. Mentre i materiali ad alta viscosità potrebbero aver bisogno di pareti più spesse per eseguire il riempimento completo dello stampo,
  • Restringimento: Il materiale con un valore di restringimento elevato potrebbe aver bisogno di pareti più spesse. Quindi, possono tenere conto delle variazioni dimensionali durante il raffreddamento.
  • Forza e flessibilità: Le proprietà meccaniche, ovvero la resistenza alla trazione e la flessibilità, determinano lo spessore della parete per prestazioni ottimali.

2. Requisiti di progettazione

I seguenti requisiti di progettazione possono influenzare lo spessore della parete.

  • Requisiti funzionali: Tutto dipende dalla parte che devi produrre. Se è una parte strutturale, allora le pareti devono essere più spesse in modo che possano essere rigide. D'altro canto, la parte cosmetica avrà bisogno di pareti più sottili in modo che possano ottenere il miglior aspetto.
  • Considerazioni estetiche: Le pareti sottili possono conferire un aspetto elegante. D'altro canto, le pareti più spesse sono abbastanza resistenti e possono evitare difetti, ad esempio segni di ritiro o deformazioni.
  • La complessità del design: Le geometrie complesse possono richiedere spessori di parete variabili. Quindi, possono garantire che tutte le caratteristiche siano formate correttamente e che la parte possa essere facilmente rimossa dallo stampo.

3. Capacità di produzione

  • Progettazione e costruzione di stampi: Gli stampi ad alta precisione possono gestire facilmente pareti più sottili, mentre gli stampi più semplici necessitano di pareti più spesse per un riempimento adeguato. Quindi, possono garantire la qualità della parte.
  • Pressione e velocità di iniezione: Le macchine con capacità più elevate possono realizzare pareti più sottili e garantiscono maggiore pressione e velocità.
  • Velocità di raffreddamento: Il raffreddamento uniforme è piuttosto importante, poiché le pareti più spesse necessitano di tempi di raffreddamento più lunghi. Ciò ha un impatto diretto sul tempo di ciclo e sull'efficienza produttiva. Quindi, i sistemi di raffreddamento avanzati aiutano a creare pareti più sottili e manterranno anche la qualità.

Conclusione

In sintesi, lo spessore della parete dello stampaggio a iniezione fornisce parti di alta qualità, ben formate e convenienti. Quindi, è essenziale considerare attentamente le proprietà dei materiali e i requisiti di progettazione per aiutare i progettisti a mantenere un equilibrio. Questo equilibrio aumenterà le prestazioni e la producibilità della parte. Inoltre, è possibile utilizzare diversi software di simulazione avanzati e opzioni di prototipazione per perfezionare l'intero processo. Questi strumenti produrranno anche progetti con difetti minimi. Inoltre, i progressi nei materiali, nella tecnologia di simulazione, nel monitoraggio in tempo reale e nelle pratiche sostenibili apporteranno miglioramenti nello stampaggio a iniezione. Quindi, può ottimizzare lo spessore della parete in modo più preciso ed efficiente.

stampaggio a iniezione ad alto volume

Domande frequenti

Quali fattori influenzano la scelta del materiale nello stampaggio a iniezione?

Il tipo di materiale viene deciso in base a proprietà come resistenza alla trazione ed elasticità, microscopia elettronica, calore e resistenza chimica. Oltre a questo, dipende anche dall'aspetto e dalla levigatezza del materiale, dal suo costo e dalla sua capacità di riciclaggio.

Quali sono alcuni difetti comuni nello stampaggio a iniezione e come possono essere prevenuti?

Alcuni dei difetti più frequenti sono i segni di ritiro, che hanno origine da diverse velocità di raffreddamento; la deformazione, risultante da stress interno; e la flash, che è un accumulo eccessivo di materiale a stampaggio a iniezione linee di separazione. Questi problemi possono normalmente essere evitati rispettando le migliori procedure di progettazione e regolando i gradi di calore, pressione e altre condizioni che potrebbero influenzare il prodotto.

In che modo il software di simulazione può avvantaggiare i processi di stampaggio a iniezione?

La simulazione assistita da computer consente a progettisti e ingegneri di modellare e analizzare i progetti di stampi, la scelta dei materiali e i fattori di processo in un ambiente virtuale. Con l'aiuto di questo software, è possibile prevedere i modelli di movimento dei materiali, le velocità di raffreddamento e altre cose prima che gli stampi fisici siano progettati per l'uso. Quindi, questo aiuta ad aggiornare la qualità e la producibilità della parte.

Quali sono i vantaggi dell'utilizzo di additivi o riempitivi nei materiali per stampaggio a iniezione?

Additivi e riempitivi possono migliorare le caratteristiche dei materiali, tra cui resistenza, rigidità, resistenza alla fiamma e resistenza all'impatto. Possono anche migliorare la lavorabilità e ridurre il costo del materiale aggiungendo un volume maggiore di un altro materiale più conveniente alla resina. Tuttavia, si dovrebbe fare molto sforzo per avere compatibilità, dispersione uniforme e interferenze minime sugli altri componenti.

/0 Commenti/da
,

Thermoplastic Injection Molding Process

stampaggio a iniezione hdpe

Thermoplastic injection molding has become the most applicable plastic manufacturing process. It is renowned for producing products of high standard quality in minimal turnaround and large quantities. The increasing need for high quality plastic products in different sectors has boosted the application of thermoplastic materials.

These materials are based on polymer resins, and when heated, they turn into a homogeneous liquid that becomes solid when cooled. Injection molding employs thermoplastics and thermosetting plastics or even elastomeric materials to form high-performance moldable parts or products. Newer technologies in injection molding thermoplastic and better molds have enabled the reduction of costs, better looks, and better manufacturing prospects.

Why Are Thermoplastics Materials Used in Injection Molding?

 

Thermoplastics are used in injection molding since they melt at high temperatures and crystallize at low temperatures. This property makes them ideal for being recycled and formed into different forms and structures. They are the most preferred materials in industries due to their flexibility and versatility of use.

thermoplastic injection molding

How To Produce Injection Molded Thermoplastic Products?

Thermoplastic injection molding is one of the most fundamental processes in contemporary production. It entails the creation of a variety of plastic products through the employment of thermoplastic polymers.

Step 1. Appropriate Material Selection

The material type used determines the final product’s functionality, appearance, and durability. Select materials by considering their mechanical properties, heat stability, and specific use.

Step 2. Material Preparation

This process entails drying raw plastic pellets to eliminate moisture. Because moisture content significantly impacts and is destructive to the melting process and the molded part. These prepared pellets are then fed into the hopper of the injection molding thermoplastic machine through a conveyor belt.

Step 3. Melting

The plastic pellets are melted in a barrel which entails a reciprocating screw. These pellets then take the form of molten lava or red hot liquid. During this phase, temperature controls are crucial to obtain the right consistency and the flow of the molten plastic to the required standard.

Step 4. Injection

As the name suggests, the molten plastic is injected into the mold cavity by applying highly controlled injection pressure. The precise control over this process determines the part’s exact specifications and finishes. The resulting parts are then cooled down and solidified at optimal conditions.

Step 5. Ejection

The required part is then taken out from the mold by using ejector pins after the solidification. This process must be timed and controlled so that it does not harm the part and that it is released properly.

Step 5. Post-Processing

This phase is typically used to cut to shape parts into desired shapes. The parts can be painted, anodized, trimmed, polished, etc, depending on the required functionality and aesthetics.

What are the Critical Parts of a Thermoplastic Injection Molding Machine?

A thermoplastic injection molding machine is made of several parts. Some commonest parts include;

Clamping Unit

The clamping unit tightly holds the two parts of the mold to ensure that they do not open during the injection. It has to apply enough force to resist the force exerted by the molten plastic being injected to ensure that the mold does not open and the part is well formed.

Injection Unit

The injection unit, which is said to be the heart of the machine, is in charge of heating the plastic material and injecting it into the mold cavity. It has a heated barrel with a screw that moves back and forth to force the plastic through a nozzle into the mold and maintain a steady supply of material.

Dwelling and Cooling System

Once the molten plastic has been injected into the mold, the dwelling and cooling system keeps pressure to guarantee that the plastic occupies all the mold cavities and solidifies into the right shape. Cooling is a very important process in the reduction of the cycle time as well as enhancing the quality of the final product.

Ejection Process

After the plastic has been set, the ejection process starts. The mold is opened, and the ejector pins, which are provided on the side of the mold, throw out the finished part from the mold cavity. This process must be done carefully and at the right time so that the part is not damaged and the removal is done well.

Mold Tool

The mold tool is a negative one and is made from steel or aluminum and forms the final product. It defines the surface finish and size of the product. The tool has two halves that are connected at the center and which are injected apart from each other.

termoplastico stampato a iniezione

Material Types Are Used in Thermoplastic Injection Molding?

The are many type of thermoplastic injection molding materials used to create molding products include;

ABS (Acrilonitrile Butadiene Stirene) is characterized by high impact strength, high rigidity, and low shrinkage. This makes it ideal for automotive components, consumer electronics, and toys where durability and mechanical stress resistance are of paramount importance. Read more about Stampaggio a iniezione ABS.

Poliammide (Nylon) has high strength, thermal stability, and wear resistance. These attributes make it ideal for use in automotive parts, mechanical products, and other consumer products that require strength and performance. Read more about stampaggio a iniezione di nylon.

Cloruro di polivinile (PVC) has the advantages of high strength, good chemical resistance, and fire resistance. Some of the uses are plumbing pipes, medical tubing, and outdoor furniture, which makes it a material that can be used in many fields.

Polietilene tereftalato (PET) is valued for its transparency, mechanical properties and food contact approval. This material is used in beverage bottles, packaging materials, and synthetic fabrics because of its strength and clarity.

PMMA or Acrylic offers sound light transmission and is not affected by weathering or UV radiation. These features make it suitable for signs, lamps, and windows where transparency and strength are desirable. Read more about Stampaggio a iniezione PMMA.

Polistirene (PS) is a lightweight material, relatively cheap, and often used in disposable cutlery, CD cases, and insulating materials because it is easy to shape and relatively cheap. Read more about Stampaggio a iniezione PS.

Poliuretano termoplastico (TPU) is characterized by high elasticity, oil resistance, and abrasion resistance. It is applied in the production of soles and insoles of shoes, flexible medical tubes, seals and gaskets of automobiles, etc. Read more about Stampaggio a iniezione di TPU.

Poliossimetilene (POM) has high rigidity, low wear rate, and good resistance to shrinkage and swelling. It is suitable for applications that call for strength and accuracy, like gears and bearings, electrical parts, and consumer products. Read more about Stampaggio a iniezione POM.

Polybutylene Terephthalate (PBT) has good electrical properties, heat and chemical resistance. It is widely applied in electrical parts, automotive parts, and under-hood parts because of its high strength and heat resistance.

Polistirene ad alto impatto (HIPS) is characterized by high impact strength and good processability. It is used in model making, sign writing, and in the housing of consumer electronic products where strength and stability are required.

Elastomeri termoplastici or TPE are materials that have characteristics of both thermoplastics and rubber and are flexible and elastic. They are applied to sealing and gasket applications, soft feel parts in household goods, and handles. Read  more about Stampaggio a iniezione TPE.

Polyphenylene Oxide (PPO) is well known for its heat resistance, low thermal expansion coefficient and electrical insulation. It is applied in automotive parts, electrical parts, and appliances that need to be hard-wearing and heat-resistant.

LCP is characterized by high mechanical strength, high-temperature stability, and good chemical resistance. It is applied in high-voltage electrical contacts, microwave oven parts, and other critical uses.

Polieterimmide (PEI) has high heat, strength, and flame resistance. It is used in aerospace parts, medical equipment, and other places where high stress is experienced.

Polyether ether ketone (PEEK) is characterized by high-temperature stability, chemical inactivity, and mechanical characteristics. It is applied in aerospace parts, automotive applications, and medical applications where strength and toughness are needed. Read more about Stampaggio a iniezione PEEK.

Polifenilene solfuro (PPS) has high heat resistance, chemical resistance, and low thermal shrinkage. It is used in automotive, electrical and electronics and in coatings that require chemical and heat stability. Read more about Stampaggio a iniezione PPS.

Styrene Acrylonitrile (SAN) is preferred for its clarity, stiffness and resistance to chemicals. These properties make it suitable for use in food containers since fats and oils are some of the things that the containers should be able to withstand. SAN is also often applied in kitchenware because of its high heat resistance and in bathroom fittings because of chemical resistance.

Acetal (Polyoxymethylene, POM) is highly stiff, self-lubricating, and has good dimensional stability. Acetal is also used in electrical insulators and consumer goods. Some common examples include; zippers and window latches, where strength and wear resistance are required.

Ethylene Vinyl Acetate (EVA) is known for its flexibility, high-impact strength, and clarity. It is a rubber like material that can be molded and recycled and is used in foam products used in sports equipment padding, footwear such as soles and insoles, and flexible packaging films.

Polyurethane (PU) is a flexible polymer that is applied to foam furniture and car seats because of its comfort and sturdiness. Also, PU is used in wheels and tires of industrial and recreational vehicles and automotive interior parts such as dashboards.

PPSU is highly heat resistant, very tough, and can withstand steam sterilization, which makes it suitable for challenging conditions. PPSU is widely used in medical instruments that are often sterilized, aircraft interiors that are exposed to high temperatures and stress, and plumbing where heat and mechanical stress are essential. Read more about Stampaggio a iniezione di PPSU.

Polyethylene Naphthalate (PEN) is a variant of PET but has better barrier properties, heat and chemical resistance. PEN is applied in packaging materials that need to be very strong and have good barrier properties and in electronics where parts need to be dimensionally stable and electrical insulating.

Polybutylene’s peculiar characteristics, like heat and pressure resistance, make it ideal for use in piping systems in hot and cold water distribution and under-floor heating systems where high temperature and pressure are required.

Polymethylpentene (PMP) is a rather special type of thermoplastic due to its transparency and heat resistance. PMP is used in laboratory equipment where chemical resistance and clarity are required and in microwave cookware because of its heat resistance and quality food preparation.

Polysulfone (PSU) is characterized by high heat resistance, strength, and transparency. These characteristics make it ideal for use in medical devices, especially those that are reusable and need to be sterilized, water filtration systems because of their stability and strength, and electrical parts where insulation and heat resistance are important.

Injection Molding Nylon

Thermoset Vs Thermoplastic Injection Molding: Key Differences

Stampaggio a iniezione termoplastica

This thermoplastic molding technique uses materials such as; polyethylene and nylon that can be reheated and recycled for second use. It is perfect for producing numerous components that require flexibility, impact strength, or clarity.

Thermoset Injection Molding

This method uses materials such as epoxy and polyester, which undergo a chemical reaction when exposed to heat and harden to a specific form. They cannot be reshaped once they have cooled down. It is used where high strength, heat or chemical resistance is required, but unlike thermoplastics, they cannot be recycled

Therefore, the major distinction is that thermoplastics can be recycled through melting and thermosets are permanently molded and cannot be remolded, providing different strength as per the requirement.

Industrial Applications of Thermoplastic Injection molding

Industria automobilistica: Thermoplastic injection molding is widely applied for fabricating interior to exterior components of automobiles like dashboard parts, bumpers, and door panels of cars. It is also useful for creating under-the-hood parts such as fluid reservoirs and housings because of its strength and accuracy.

Settore medico: In the medicare sector, thermoplastic injection molding is very significant in the manufacturing of disposable syringes, surgical instruments, and enclosures for medical devices. Due to its precision in developing complex patterns, it is essential to develop parts utilized in diagnostic tools and prosthetics.

Elettronica di consumo: In electronics, this molding process is used in the production of enclosures of smart phones, remote controls, and computer parts, among others. It is also used in the fabrication of battery casings and connectors because of its strength and versatility of shape.

Construction Industry: In construction, thermoplastic injection molding is applied in the production of pipe fittings, plumbing parts, and electrical enclosures because of the strength and durability of the material. It is also applied in the production of insulating materials and window frames due to its strength and heat resistance.

Toys and Recreation: This molding process is used in creating action figures, puzzles, and boards games that have designs that are complex. It is also used in the manufacture of outdoor items such as garden implements and children’s play equipment since it can yield strong and safe products.

Household Products: Thermoplastic injection molding is vital in the production of kitchen appliances, containers, and utensils because of the heat and chemical resistance. It is also used in making storage bins and cleaning tools due to its strength and simplicity.

Thermoplastic Injection Molding: Common Defects & Remedies

Below are typical challenges encountered during the process and strategies to address them effectively:

Insufficient Filling: This is so when the mold is not fully filled. To address this, one may increase injection speed or pressure, check the temperature of the material, or increase the size of the gate.

Flash Formation: This is a condition where there is the formation of a thin layer of plastic on the edge of the part after it has been molded. This can be solved by either lowering the injection pressure or clamping force or by checking the mold for any damages.

Warping: If the part distorts during cooling, then consider uniform cooling temperature, cycle time to optimal state.

Sink Marks: These are small contours on the part’s surface and normally occur in varying sizes. To prevent these, increase the cooling time or reduce the holding pressure.

Burn Marks: These occur when a material is overheated or air is trapped and may cause black or brown discoloration on the part surface. This can be overcome by reducing the melt and mold temperature and, at the same time, increasing the injection speed so as to avoid overheating or the formation of air pockets.

Such changes should enhance the quality and productivity of the injection molding process.

Riassumendo

Thermoplastic injection molding remains one of the most significant pillars of innovation that offers flexibility and effectiveness in developing quality products. It is used in automotive and medical industries, consumer electronics and many more industries proving its versatility and efficiency.

Companies like Sincer Tech are the best examples of plastic injection molding services that provide full-service solutions with a focus on quality and accuracy. Our company specializes in overmolding and insert molding and uses a variety of materials to guarantee that each product is of the highest quality.

They offer a wide range of thermoplastics, and their experience in prototype molding and mass production makes them among the best. Whether it is a prototype or a mass production project, Sincere Techs’ dedication to the advancement of technology and the production of high-quality products is evident in all of their work.

/da