What is injection molding surface finish

Injection modlign surface finish is the post surface finish process added to the plastic injection molded parts, those include painting, silk-screen, chrome plating, pad printing, thermal transfer printing,water transfer printing, laser engraving, and so on, all of those addtional process we call surface finish process.

When you start a custom plastic injection molding project, at first you need a plastic mold to produce plastic molding parts, after that you may have additional options for your plastic parts, like some secondary process to your plastic molding parts, these secondary processes need to add on after molding.

 

There are some of the plastic injection molding surface finish to the molded plastic parts, this will make the plastic injection molding parts look better, or have more information or special surface finished requirement, before doing this you need to know each type of secondary process, to make sure if those process can meet your requirement, let us discuss below some of the most popular secondary processes which will be used to the injection molding parts.

We are not only offering plastic mold/molding service but also offer additional, value-added services to support you get your molded parts finished, assembled, packaged, and shipped directly to your storage house, then you can sort them on the market directly.

Plastic injection molding surface finish include:

Printing

If it is needed to print or pattern on the surface of plastic products, there will be several ways as follows.
1. Screen Printing
This Method is the most common and used method, which is generally suitable for printing with a small plane or radian.
2. Surface Printing
Principle of Curved Surface Printing
Curved surface printing is to first place the printing ink into the intaglio engraved with characters or patterns, copy the characters or patterns onto the curved surface later, transfer the characters or patterns onto the surface of the molded product by using the curved surface, and finally solidify the printing ink by means of heat treatment or ultraviolet light irradiation.
Process of Curved Surface Printing:

A. Debinding of shaped products
B. Surface treatment of molded products (if necessary)
C. Printing
D. Curing process of the printing ink
E. After-treatment such as excessive coating (if necessary)
Simple Process of printing as below
A. To put the printing ink into the intaglio
B. To scrape off excessive printing ink
C. To extrude the curved surface to obtain the printing ink
D. To transfer the printing ink with the curved surface to the surface of the molded product
E. To clean the curved surface and layout (if necessary)

Pad printing

The figure or pattern is printed on a rubber plate or rubber-covered roll by the plate first, and then it is transferred to the surface of injection mold parts on the rubber plate or rubber-covered roll.
Advantages: Several colors can be applied in one operation.
Disadvantages: Low productivity, inability to obtain stronger opaque marks, how to select the appropriate rubber plate or rubber-covered roll and oil quantity first, etc.

Hot Stamping

It relates to a method for manufacturing colorful package embossed patterns or fonts on the surface of the injection mold parts by using colorful foil and a hot mold engraved with patterns or fonts under the control of temperature and pressure. Its operation only needs to apply pressure to the required area of the product through the colorful foil by using the hot mold arranged on a fixed press machine.

Painting

The most common methods for surface treatment (color) of plastic products can be divided into:

A. For a common coloring, this kind of paint is mostly sprayed by hand and does not have strong friction resistance and is easy to drop.

B. For Grade PU gloss oil, this method is to spray a layer of PU gloss oil on the surface to achieve friction resistance and gloss after drying the primer. Many surfaces of general household appliances or daily necessities are treated with PU.

C. UV-grade gloss oil This method sprays a layer of UV gloss oil on the surface after the primer is sprayed, and the gloss, the hand feels and friction resistance can all achieve very ideal effects. This method is commonly used for mobile phone mould products and communication mould products.

Electroplating (Chrome plating)

Plastic Electroplating (Plastic Chrome plating) is just called the process of depositing metal or alloy on the surface of a workpiece by electrolysis to form a uniform, dense and well-bonded metal layer. Its simple understanding is a change or combination of physics and chemistry.

Purpose of plastic molding electroplating:
a. Corrosion protection
b. Protective decoration
c. Abrasion resistance
d. Electrical performance: It is provided the coating with conductive or insulating performance according to the working requirements of parts.
e. technological requirements

It is relatively complicated for the process of forming a uniform, dense and well-bonded metal or alloy deposits on the surface of the workpiece by electrolysis, but it has many advantages such as more types of metals deposited, various colors available and relatively lower price compared with similar processes. Go to plastic chrome plating page to know more about this injection molding surface finish.

Cause of Failure	Processing method
Insufficient material feed for mold	To increase feed
Insufficient amount of melted material	Be an appropriate feeding and a moderate increase of back pressure
Injection pressure is too low	To increase the process of melting glue metering stroke
Holding pressure is too small	To increase injection pressure
Injection time is too short	To increase injection time
Injection speed is too slow	To increase the firing rate
Unbalance gate size	To adjust the size or position of the mold entrance equally
Blockage of nozzle	To make demolition and cleaning
Material temperature is too high	To reduce the material temperature
Incorrect mold temperature	To adjust the appropriate mold temperature
Insufficient cooling time	To increase the cooling time
Poor exhaust (venting)	To arrange an exhaust hole at the shrinkage part.
The material barrel is too large	To replace the smaller gauge material barrel
Abrasion of Screw Non-return valve	To make demolition and overhaul
Uneven wall thickness in the part design	To increase injection pressure

If you have any platic injection molding project in hand that needs make molds and injection molding surface finish service, you are welcome to contact us. We are one of top 10 plastic injection molding companies in China that offer custom injection molding and surface finish for molded parts, we will offer you the best price in 24 hours.