Overmolding is also called 2 times injection molding in China. Compared with the third-party material bonding, overmolding process makes the process faster and more cost-effective, it has been widely employed in plastic design.

Over molding are categorized into 3 types: insert molding, double shot molding, co-injection molding.

Insert molding: The most commonly used to mold soft elastomers to rigid plastics, insert molding is the most economical way to do overmolding. In the insert design, the hard segment has been separated into tools in advance, and then eject the soft materials in.

Elastomers are adhesion bond, which can be mechanical locks, chemical and other methods. In order to achieve chemical adhesion, the elastomer must be sufficiently heat to melt the surface of the hard segment to achieve chemical bonding.

This injection mold making project is an electrical switch plastic holder, the material is PC-ABS.

Basic part information

• Part size: 47.64 x 73.59 x 16.59 mm
• Plastic material: BAYBLEND FR3010
• Finish: VDI-18
• Color: black
• Production volume: 10K

Welding lines are a typical defects for injection molded parts with many hole features, such as computer key board typically, the hot resin flow around the little inserts and melt flow meet each other on other side where the welding line occurs, this is how welding line occurs, melt flow temperature always drop while melt resin flow over the mold cavity, that is why the welding line can only be optimized but can not be completed removed if you simply use higher mold temperature, in some other cases, changing gate position would just change the welding line to a less critical location, but for a product similar like computer key board, neither mold temperature or changing gate location would work, as a consumer product, the surface finish is quite critical thing, so as you can see now most of the key board product was painted nicely to cover the welding line defects.

Here is an example we have made for one of our clients from US.

This is a mesh basket, at the beginning, the customer decided to go with high temperature ABS material. As usual, we discussed the part details such as parting line, gate type/location, draft angle, wall thickness and the other potential issues/proposal with the customer before mold making, this is called DFM process.

Recently we had done a succeed mold and molding project for a US company, it's a type of a remote controller, project went smooth but I would like to summarize it and point out a few key points, first we take a look on the project.

It's consisted with front case, back case, cover, and silicone pad, there is a BOM for the whole product, but due to Non-disclosure agreement, we can't give more details how it was designed.

Basic part information:

• Part size: 80x45x30mm
• Plastic material: ABS /silicone
• Finish: SPI-B-2
• Color: blue/black
• Production volume: 10K

We made one 1+1+1 family mold for the front case, back case, cover, actually the front case and cover are in blue, back case is in black, the question is how to do 2 different color in one mold? -- we design a turntable gate so we can mold one color by sealing the other cavities, by this way we only need one mold, even the molding productivity is a little lower but given the cost of an extra mold and only 10K production volume, this is still an economic way to go.

Plastic injection molded parts have many applications on architecture industrial, such as PVC water pipes, plastic gliders on windows, shelf support, hangers, handles etc. ACO Mold has rich experiences to help customer to customize their own architecture plastic parts.

Here is an example to show you how we work with a North American company from mold design to injection molding production for a glider/slider on windows step by step.

Basic information
Glider size: 0.6x0.5x0.3 inch
Plastic material: PA66+GF30
Finish: SPI-B-2
Color: nature
Demand volume: 10K-20K/ year

ACO Mold are engaged in injection mold making for plastic packaging housing/cases in packaging industrial, usually plastic packaging housing/cases are made in PS or PC, with high polish surface, which required SPI-A mold surface finish, most common choices for steel are NAK80, 1.2083, 1.2344.

Injection mold making is a customized process, ACO Mold engineers work closely with customer to understand their requirements and make proper solution to achieve the best possibility,we are not simply a mold manufacture to deliver the parts according to design, we offer solutions and deliver satisfaction.

From this project, you can see the product designs from customers are not always the optimized one, sometimes the defects of the molded parts are caused by product design problem, the purpose of DFM analysis made by ACO Mold is to avoid such defects before mold making.

ABS is the initial letters of Acrylonitrile Butadiene Styrene, it is a high strength, good toughness, easy molding of thermoplastic polymer material. Plastic ABS resin is the largest output, the most widely used polymer in injection molding industry, ABS material widely used in auto parts, household appliances, consumer products, packaging materials, industrial parts etc... ABS Molding Service »

There are plastic injection molding manufacturers in China which have state of the art equipment, equal to the best of the injection mold makers in the US, Germany, Switzerland or Japan. The same is true of the precision molding machines and injection molding companies. There are manufacturers in China which are capable to produce state of the art molds and precision molded plastic parts. The Chinese are getting better and better every year... Precision Molding Service »

A custom plastic part requires a unique design that means customize for each individual company, specially made tooling and professional skill; you need to invest as much intelligent, money and time as it takes to get a quality part. ACO Mold, one of the top 10 manufacturers of custom injection molds in China, can help you from custom plastic parts design to mold making and injection molding, to ensure that your custom plastics are made quality-conform and cost effective... Custom Service »

I am working on an air pressure expulsion mechanism for plastic injection molds, to avoid the use of ejector pins and eliminate or reduce the ejector pins marks. I would like to know other possible solutions to reduce the marks when you eject the parts from the cavity. I will appreciate your comments or ideas!

I assumed that it is plain tap water and serves to heat and possibly cool the mold. I introduced the possibility of using an automotive coolant and here it would be a heating fluid. Certainly pH would be important and I assume should be kept as near to pH7 as possible since aluminum oxides can exhibit amphoteric properties. There are various inhibitors that can be used in these situations, but misuse or lack of monitoring can even accelerate the corrosion.

I don't know how many molds you have, but you might want to try all three types. Depending on various factors, the IAT may cause deposits and affect the overall performance, so I would be more inclined to try the OAT or the HOAT coolant. The use of such coolants in your circulating system may be an inexpensive way to fix your problem.