Injection Mold Making Project for Plastic Protective Case

Recently, JAVE Mold made a plastic protective case for an electronic product, made by ABS, here we share with you the injection mold making process and some solid experiences to fix sink mark defects.

Basic part information:

• Part size: 138.58*21.01*114.30 mm
• Plastic material: ABS
• Finish: SPI-B1
• Color: Grey
• Production volume: 5K

The plastic protective cases are consisting of two parts, the upper and bottom covers. Considering of low volume production, 5k, in order to save costs for our customer, JAVE Mold go 1+1 mold solution.

Basic mold information:

• Mold type: 2-Plate
• Gate type: Side Gate
• Cavity number: 1+1
• Material: ABS(PA-757)
• Shrinkage: 5/1000
• Molding Machine (Tons): 160T

Before making the injection mold, JAVE Mold do DFM analysis of the plastic protective cases,  and verify some important information with the customer, like parting line, gate position, ejection, etc.


After the verification with the customer, JAVE Mold made 3D design layout of the injection mold.


The actual injection mold completed as following picture shows:


Injection mold making took 4 weeks, JAVE Mold did T1 sample testing on the scheduled time, but there were sink marks on the surface of the plastic case (marked by red cycles in following picture), the reason of the sink marks was the thickness is too heavy in those positions, which we had stated this risks and proposed to change that in DFM phrase, unfortunately customer insist on going forward any way with their own original design.

See below pictures, the sink mark is quite vivid on the outer surface.


JAVE Mold discussed with the customer about the sink marks, the customer agreed to send the T1 samples to check if there is any other function issue or any assembly issues, the customer did the testing, everything was great except the sink marks. JAVE Mold optimized the product design after discussed with the customer about the function and assemble of the protective cases.

JAVE Mold made a PPT to show the customer about the modification of the protective case by understanding its function & assembly before finalizing the design.


Here JAVE Mold will show you the details of the product optimization base on our experiences
There are 2 solid pillars are designed as press-in-tight function, this 2 pillars are completed solid, which is very difficult to maintain good looking on the opposite surface due to natural shrinkage phenomenon, we changed it to a cross feature with much less material and meanwhile we create a groove around the root of the cross feature to ease the shrinkage mark , see the picture below how it looks like.


Secondly, we massively reduce material on the heavy material section area (highlight in red color), to make it as even as possible with the all over wall thickness.


After modification, we set up for trail, as you can see from the picture, the sink mark problem was resolved.


T2 samples were approved fast by customer, and we go ahead for mass production.


Remark by JAVE Mold
Injection mold making is a customized process, JAVE 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 JAVE Mold is to avoid such defects before mold making.