In the production process of MIM technology, many problems can be encountered. I have roughly summarized some of these problems and their solutions, please take a look.
tiros cortos When injection-molded parts aren’t fully formed, it’s often due to short shots. This can happen when not enough raw material is injected, when there’s significant resistance to the molten plastic flow, or when mold venting is poor. Soluciones: Adjust the raw materials and diseño de molde to ensure adequate filling and proper venting.
Formación de rebabas Burr, or excess material, can form due to damage on the clamping surfaces of the mold, improper movement or fixation of the mold, or excessive pressure of the raw material. Soluciones: Repair the mold, adjust mold locking mechanisms, and regulate the pressure of the raw materials to prevent overflows.
Deformación Partes may warp due to high mold release temperatures, inconsistent cooling times across different areas, or uneven mold filling. Soluciones: Optimize cooling conditions and mold design to ensure uniform cooling and filling.
Impurezas Contaminants can mix with the raw materials or arise from material decomposition, leading to quality defects. Soluciones: Clean and control the quality of raw materials to prevent contamination.
Grietas Cracking can be a result of issues during the ejection phase of the proceso de moldeo. Soluciones: Increase the mold temperature, reduce packing pressure, lower the melt temperature, and polish the mold to facilitate smoother ejection.
Contracción A significant shrinkage of raw materials during the cooling process can cause defects. Soluciones: Adjust the cooling process and mold pressure to compensate for material shrinkage.
Burbujas Vacuums formed due to material shrinkage during cooling can result in bubbles. Soluciones: Adjust cooling conditions, handle materials properly, dry hygroscopic materials, and enhance heat removal from the tool to prevent bubble formation.
Post-Solvent Cracks Stress within the mold can lead to cracks after solvent application. Soluciones: Increase ventilation, raise mold temperature, and implement post-mold annealing to relieve stress.
Flash A failure to close the tool properly can result in flash, where excess material seeps out of the mold cavity. Soluciones: Adjust the tool for better clamping, clean the mold surfaces, and use higher tonnage machines if necessary to prevent flash.
Gate Blemishes Separation of powder/binder at the gate can cause defects at the point of entry. Soluciones: Decrease injection speed and packing pressure to ensure a smooth material entry.
Incomplete Fills Insufficient material in the cavity prior to gate freezing or material feed issues can prevent complete filling. Soluciones: Increase the shot size, packing pressure, injection speed, and venting; raise melt and mold temperatures; and ensure raw materials are properly supplied and handled.
Marcas de fregadero Poorly filled parts can lead to sink marks or depressions on the surface. Soluciones: Increase packing pressure or time, enlarge gate size, adjust backpressure for screw recovery, and manage temperatures to balance material shrinkage with fill.
Variable Component Mass Variation in shot size can cause inconsistencies in the part weights. Soluciones: Clean the check ring and increase recovery backpressure to ensure consistent shot sizes.
By understanding the root causes of these defects and implementing the suggested solutions, manufacturers can greatly improve the efficiency and quality of their procesos de moldeo por inyección.
This blog post is intended to guide manufacturers in identifying and resolving common defects in moldeo por inyección de plástico, ensuring a smoother and more reliable production line.