What is the shrinkage rate of ABS?
3 Answers
ABS has a normal shrinkage rate of 0.45%. Introduction to ABS: ABS material is a graft copolymer composed of three monomers: acrylonitrile, 1,3-butadiene, and styrene. ABS is not affected by water, inorganic salts, alkalis, and various acids, but it can dissolve in ketones, aldehydes, and chlorinated hydrocarbons. Exposure to glacial acetic acid or vegetable oil can cause stress cracking. ABS has poor weather resistance and tends to degrade under ultraviolet light; after six months outdoors, its impact strength decreases by half. Introduction to shrinkage rate: Different raw materials have different shrinkage rates. Generally, fibers with high hygroscopicity will expand in diameter and shorten in length when soaked in water, resulting in a higher shrinkage rate. For example, some viscose fibers have a water absorption rate of up to 13%, while synthetic fiber fabrics with low hygroscopicity have a smaller shrinkage rate. Density also affects shrinkage rate. If the warp and weft densities are similar, their shrinkage rates will be close. Fabrics with higher warp density will have greater warp shrinkage, and conversely, fabrics with higher weft density will have greater weft shrinkage.
The shrinkage rate of ABS generally ranges between 0.4%-0.9%, depending on how you use it. Last time when I helped a friend make automotive interior part molds, actual tests showed fluctuations between material batches. For example, it shrank to 0.7% during low-temperature low-pressure injection molding, but dropped to 0.5% after increasing the mold temperature. Structural factors must also be considered separately – parts with more reinforcing ribs shrink more noticeably due to uneven cooling rates. It's recommended to obtain the material property sheet for the specific grade from the supplier before production – this data is far more accurate than random guesses.
The shrinkage rate of ABS is actually quite flexible, typically fluctuating around 0.5%. When manufacturing rearview mirror housings, we observed a pattern: areas with wall thickness exceeding 3mm tend to shrink up to 0.8%, while thin-walled regions are controlled within 0.4%. Processing temperature is also crucial - setting the barrel temperature to 230°C reduces shrinkage by 0.2% compared to 200°C. For precision part designs, it's advisable to leave a 0.6% margin and fine-tune through holding time.
