ABS注塑成型常见问题解答

As a thermoplastic, ABS melts at around 105°C (221°F), allowing manufacturers to inject it into a mold. When it solidifies upon cooling, it takes the shape of the mold. ABS is favored over other thermoplastics for producing rigid, durable products with a high-quality surface finish. See the wide range of ABS injection molding applications here.

对于使用ABS材料制造小型零件而言，1.14毫米至1.2毫米的壁厚最为理想，特别是在必须避免出现凹陷的情况下。 为了平衡成型效率与结构刚度，功能性部件的理想壁厚范围为1.5毫米至2.5毫米。较大部件的最大壁厚通常小于3.56毫米。然而，壁厚较大的部件容易出现翘曲、冷却时间过长以及表面变形等问题。.

对于肋条、带有纹理的表面或较深的部位，应将脱模斜度增加至2°或更大，以最大限度地降低脱模过程中造成损坏的风险。作为一条经验法则，纹理深度每增加0.001英寸，就应额外增加1°至1.5°的脱模斜度。这是因为表面越粗糙，产生的摩擦力就越大。.

Optimizing the ribs helps to maximize structural strength and avoid common molding defects. The table below provides a guideline on best practices for rib optimization.

Specialized grades are used for applications where the product is expected to have specific requirements. Examples of specialized grade ABS include high-impact ABS, flame-retardant ABS, high-heat ABS, plating-grade ABS, and transparent ABS. Read the detailed description of the different types here.

模塑PC的抗拉强度约为10,442 psi，而ABS仅为5,874 psi。在热性能方面，PC在较高温度下（132°C至138°C）仍能保持其强度。 而ABS则在97°C至100°C左右开始变形或失效。.

ABS的耐候性和抗紫外线性能较差。长期暴露在阳光下会发黄并变脆。这限制了其在户外用品中的应用。此外，由于ABS的抗拉强度较低，其在发生断裂前所能承受的结构载荷也比PC小。如果加工不当，它更容易发生翘曲。.

The processing temperature of PC is higher (280^oC to 320^oC) and requires slow, controlled cooling to prevent extreme warpage and maintain the product integrity.

The mold cavity must be polished to an SPI A-level finish using diamond buffing. This yields a surface roughness (Ra) of 0.012 to 0.10 μm. The mold material must be made of hardened steel (e.g., S136) that maintains a high polish during high-volume production. The mold temperatures should be higher too (60°C – 80°C)

The real-world application will decide the speed to prevent defects like weld lines, burning, or short shots. In some instances, manufacturers sometimes use a multi-stage approach. Here, the speed starts moderate and is gradually adjusted depending on geometry. In some cases, different speeds are used for different sections. Thin-walled or high-gloss parts need faster speeds to ensure proper filling.

If the injection speed is too slow, the plastic will cool before fully filling the mold cavity, leading to short shots. If the speed is too high, it will cause excessive frictional heat, leading to burning. In terms of efficiency, faster injection speed reduces the total filling time and cuts down the cycle time.

Although the ideal duration is 5 to 6 minutes, higher temperatures will require shorter residence time. The ideal barrel temperatures are often 225°C to 250°C.

The cause of these defects is often improper temperature control, excessive injection speed, inadequate venting, and inadequate drying of material before molding. See the full explanation of the causes of the different defects here.

The hygroscopic nature of ABS allows it to absorb moisture from the air. Improper drying below 0.1% moisture content before molding allows this moisture to cause silvery streaks or ‘starburst’ patterns on the surface of the molded part.

Shrinkage happens when the thick, inner sections of the part solidify more slowly than the outer skin, pulling the surface inward. Some of the common causes of sink marks in ABS injection molding include:

• Non-uniform wall thickness
• Excessive thickness
• Insufficient packing or holding pressure
• Excessive melt temperature
• Insufficient cooling time
• Ineffective cooling channels
• Poor venting

Short shots will mostly arise when the processing parameters are not properly optimized or when there is a mold design flaw. In most cases, the problem can be solved by optimizing mold design and processing parameters as highlighted in the table below.

Variation in wall thickness leads to uneven shrinkage. Likewise, excessively high or unbalanced mold temperature can cause improper cooling, which leads to warping. High shear forces resulting from high injection speed can lead to twisting or warping.

If the mold is not adequately vented, during filling, the air has nowhere to go, leading to burn at the end-of-fill zones. Air can also get trapped in ribs and bosses because of their enclosed nature.

If the ABS resin is not sufficiently heated, it will become too viscous and will not evenly fill the mold, leading to flow lines. Also, if the mold surface is too cold, the molten plastic will cool quickly upon contact, forming a ‘skin’. The remaining molten plastic must force through the skin, which leaves visible marks.