The issues you mentioned, such as scrap jumping, waste plugging, poor flaring, and uneven trimming, are common molding defects that can occur during the injection molding process. These defects can impact the quality and consistency of the molded parts. Let’s address each of these issues separately:
- Scrap Jumping: Scrap jumping, also known as sprue sticking or runner sticking, occurs when the sprue or runner sticks to the mold instead of being cleanly ejected. This can result from inadequate mold release, improper ejection system, or poor temperature control. Ensure that the ejection system is functioning correctly, use appropriate mold release agents, and maintain proper mold temperature to prevent scrap jumping.
- Waste Plugging: Waste plugging refers to the blockage of material flow in the mold, leading to incomplete filling or trapped air pockets. This issue can be caused by improper gate design, inadequate venting, or inadequate injection pressure. Verify that the gate design and size are suitable for the material being used and ensure proper venting to allow trapped air to escape during filling.
- Poor Flaring: Poor flaring or flashing occurs when excess material protrudes from the parting line or mold seams. This defect can result from excessive injection pressure, poor mold alignment, or worn mold components. Check for proper mold alignment and wear on the mold surfaces, and adjust injection pressure as necessary to reduce flaring.
- Uneven Trimming: Uneven trimming of the molded parts can occur due to improper trimming tools or inconsistent trimming techniques. Ensure that the trimming tools are sharp and in good condition, and that operators are trained to perform even and consistent trimming.
To address these issues, it’s crucial to conduct a thorough analysis of the injection molding process and mold design. Work closely with experienced mold engineers and process technicians to identify the root causes of the defects and implement appropriate solutions. Regular maintenance of the mold, proper process control, and adherence to best practices can significantly improve the quality of the molded parts and reduce the occurrence of these defects.
- Scrap jumping
a. If the punch is not long enough, replace the punch according to one material thickness plus 1mm when the punch cutting edge cuts into the female die
b. Excessive clearance of female die Cut in tool to reduce clearance or use coating machine to reduce clearance
c. The punch or template is not demagnetized. Use a demagnetizer to demagnetize the punch or template
- Waste plugging
a. The blanking hole is small or deviated, and the blanking hole is enlarged to ensure smooth blanking
b. The blanking hole has a chamfer. Increase the blanking hole to remove the chamfer
c. Cut taper or reverse expansion hole to reduce the length of straight wall position
d. The straight wall position of the knife edge is too long and the reverse side is drilled to shorten the straight wall position of the knife edge
e. The cutting edge collapses, resulting in a large flaring edge, and the material is blocked and the cutting edge is reground
- Poor tip
a. The edge is broken, causing excessive flaring and regrinding the edge
b. The clearance between the punch and the female die is too large, cut the line into the block, and re fit the clearance
c. Straight wall position of polishing edge with poor finish of concave die edge
d. If the clearance between the punch and the die is too small, the die shall be saved again, and the clearance shall be provided
e. If the ejecting force is too large, pull out the flaring edge reversely to replace the spring, reducing the ejecting force
- Uneven trimming
a. Positioning offset adjusting positioning
b. Unilateral forming, pulling, increasing pressing force, adjusting positioning
c. Design error, causing unevenness of the cutter, and cutting the edge insert with new lines
d. Feeding is not allowed to adjust the feeder
e. Recalculate the feeding step if the calculation is wrong, and reset the tool position
Scrap jumping, waste plugging, poor flaring, and uneven trimming are common problems that can occur during mold processing. Scrap jumping occurs when the mold produces products with excessive burrs or flash, which affects the product’s appearance and performance.
Waste plugging occurs when the mold cavity or runner is blocked, leading to incomplete product formation or even equipment damage. Poor flaring occurs when the product’s edge is uneven, leading to poor aesthetics and performance. Uneven trimming occurs when the trimming process is not precise, leading to product size deviations or other quality issues. To avoid these problems, mold processing technicians need to have a deep understanding of the processing parameters, materials, and equipment used in the process. Proper training and regular maintenance can also help to prevent these issues.