Subsequent processing of powder injection molding products

1. Overview
The key reasons for using powder injection molding is able to reduce costs. In many cases, the PIM is only used as a near net shape, the final details of the product also need to subsequent processing.Such high grinding and machining processes usually cost, using the PIM for final machining of rough sometimes easier. This means that through the strict PIM process control to increase the product’s final features than the subsequent processing cost is much higher.

Roughly 60% of PIM products at least after the sintering process is required to obtain the desired features and precision.Heat treatment can improve product performance, the plastic is the most common process used to ensure that the appropriate size. When the follow-up processing is adopted based on the following reasons:

Heat-treatment is used to improve the hardness and strength.
Removal process defects, such as the gate mark.
Alignment or straighten parts.
Key to grinding surface to meet the tolerance requirements.
The surface alloying or carburizing in order to improve the hardness.
Increase precision holes or fine thread on the parts.
Plating or painting.
Connecting a plurality of parts or assembly into a single component.
The outer surface of the polishing.
The surface peening in order to improve the fatigue life.

Used in a variety of grinding or densification process removes pore

In addition, the products need to be the final inspection, to ensure that the design of the product requirements.Thus, PIM parts produced are usually not removed from the ends of the sintering furnace.The successful implementation of these final steps can be adjusted to the desired product service working condition.Usually, the subsequent processing of PIM products and other processing route, the process USES is the traditional manufacturing procedures.
2.The Deformation Process

1) Cold deformation
Belongs to the deformation of the parts may be slightly after sintering, by cold deformation process will be flat or straight.Smaller size distribution can be achieved by shaping.Cosmetic procedures commonly used small deformation, usually confined to a surface or feature.Brittle material lack of this kind of forming ability, which leads to the lack of production of flexible in terms of the final size.For mass production, plastic is done using automated equipment.

2) The thermal deformation
The thermal deformation and thermal densification technology can improve the performance of the end of the product density and realize full densification.Such a process is needed in high reliability requirements of applications, such as electronic, medical, dental, aerospace and oil drilling parts.
Achieve full densification is a way in the later stages of the sintering cycle to pressure parts processing.The initial stage of sintering cycle in a vacuum, and then to the furnace running in high pressure gas before cooling.This is usually used in the manufacture of cemented carbide.This process requires a thick wall of vacuum sintering furnace, with safety load is under great pressure, the pressure can up to 100 mpa.After the process, material performance can be improved obviously.PIM steel (Fe – 0.8 C), for example, after the sintering strength of 500 mpa, the elongation is 5%, and increase the thermal deformation process, the length can be increased to 720 mpa, the elongation can be increased to 23%

3. Machining
Machining products from sintering process to remove the related materials, and the deformation process only parts to change shape without changing the quality contrasts.All common machining process can be used in the PIM products.For PIM materials, machining quantity to reduce as far as possible, just used to adjust the size or features in addition to machining is difficult to guarantee.Some companies adopt the PIM green near net shape manufacturing parts, intentionally by machining after sintered to get the key size, the process is similar to add a machining process after casting.In this case, the hardness of the material will affect the service life of cutting tools, so if possible, machining should be arranged before any hardening heat treatment, but some of the material in heat treatment can produce warp or size change, so need to be machined or put it off until the final grinding process.