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Many overseas buyers and product designers often get confused about shrinkage rate setting for two-color injection molds and overmolds. Improper shrinkage reservation will cause product deformation, gaps, misalignment and poor fitting during mass production.
As a professional precision mold manufacturer, Andes Industrial shares the correct industry standards for shrinkage setting.
A common misunderstanding is setting a separate higher shrinkage rate for the second-shot soft rubber.
The correct design principle is as follows:
First shot (hard plastic)
Shrinkage is reserved according to the properties of hard materials such as ABS, PC and PP, with a standard range of 0.4% – 0.8%.
Second shot (soft rubber TPU/TPE/TPR)
Do not set independent shrinkage. The second shot must fully follow the shrinkage rate of the first-shot hard plastic.
The first-shot hard plastic parts have already completed shrinkage and shaping. The second-shot soft rubber is wrapped strictly around the formed hard parts. If the natural shrinkage rate of soft rubber is adopted separately, it will directly lead to position deviation, poor wrapping and assembly failure.
For traditional insert overmolding:
(1) The inner hard plastic inserts are pre-molded and fully shrunk in advance.
(2) The outer soft rubber layer strictly follows the fixed size of the hard inserts, with no additional shrinkage reserved for soft materials.
This method ensures tight fitting, no gaps, no warpage and stable mass production.
Unprofessional shrinkage design will result in:
(1) Product warpage and deformation
(2) Unstable dimensions in mass production
(3) Poor bonding between hard and soft materials
(4) High defective rates
At Andes Industrial, we confirm all shrinkage parameters strictly during the DFM design stage for all two-color molds and overmolds. We adjust data according to material hardness, product structure and assembly requirements to ensure stable and qualified final products.
Precise parameter control is the core of high-quality precision molds. We keep delivering reliable solutions for two-color molds, reversed molds, automotive molds and overmolds to global customers.
If you have any technical questions about mold shrinkage, mold design, or custom injection mold projects, feel free to contact our professional engineering team anytime. We provide free technical support, DFM analysis and professional mold solutions for your project.
Email: mold@andesind.com
We sincerely welcome global customers to discuss cooperation and create win-win results together.
At Andes Industrial, we adhere to steady and professional business development in the precision injection mold industry.
Instead of blind mass promotion, we focus more on long-term brand building and Google website optimization. We carefully optimize every product page, including product titles, detailed descriptions, image presentation and overall page layout, to make our professional mold strength more intuitive and clear.
We are committed to presenting our real factory strength, mature mold technology and rich export experience to global buyers through official websites. Our main products cover 2K double-color molds, reversed molds, automotive molds and daily-use product injection molds.
We believe that high-quality cooperation comes from mutual recognition, not passive disturbance. By improving online display and professional influence, we let sincere overseas customers find us initiatively.
Andes Industrial always focuses on technology research, quality control and customer service. We keep improving our comprehensive strength to create reliable and win-win cooperation with global partners.
If you have any technical questions about mold design or custom injection mold projects, feel free to contact our professional engineering team anytime. We provide free technical support and DFM analysis for your project.
Email: mold@andesind.com
We sincerely welcome global customers to discuss cooperation and create win-win results together.
