Pistol MIM Parts

Product Introduction

Product Application
• MIM titanium gun trigger
Figure 1 shows a MIM titanium trigger produced for an Italian gun manufacturer. The background is the green part (molded), the foreground is the sintered part.

Figure 1 Metal Injection Molded Titanium Gun Trigger Made by Mimest Spa, Italy

Metal injection molded titanium parts are currently limited to high performance applications (in terms of fatigue properties, biocompatibility and light weight) due to high material costs, or luxury consumer products where titanium adds exclusivity and marketability.
With the price of titanium powder falling, the MIM component market is expected to grow significantly.
The

• “Safe and Arm” rotor
The military "safety arm" rotor shown in Figure 2 is used in explosive devices for US Department of Defense applications. 316L stainless steel parts are produced by metal injection molding with a density of 7.6 g/cm3. Its important properties include an ultimate tensile strength of 75,000 psi, yield strength of 25,000 psi, 50% elongation and a hardness of 67 HRB.

Fig. 2 Safe and arm rotor produced by FloMet LLC, USA. (Photo courtesy of MPIF)

Complex shapes have many outer radii and angular surfaces. At least twelve functional features and surfaces are geometrically controlled by concentricity, profile and true position tolerances.
The component is assembled into the casing to provide two levels of safety for explosive devices. Pistol MIM Parts replaced zinc die castings whose mechanical properties ended up not being consistent enough to pass proof testing.

• Pistol Swept Grip Safety Components
The safety part of the pistol (Figure 3) is used in the 1911 type 45 caliber pistol produced by the American Colt Manufacturing Company. The complex MIM 17-4 PH stainless steel part produced has a density of 7.6gcm³. 

Fig. 3 The pistol sweep-up grip safety component produced by Megamet Solid Metals, Inc. of the United States. (Photo courtesy of MPIF)

The upswept design of grip safety components traditionally employed in investment casting previously required extensive secondary machining. In addition to increasing productivity and producing more uniform parts, switching to the MIM process has resulted in shorter customer lead times and significant cost savings.
This part performs several functions: it stops the trigger from firing, protects the hammer from striking or injuring the shooter's hand as the pistol cycles, and interacts with the shooter's palm for comfort. Colt conducted a 10,000 cycle test to validate the part.

Production Process
Powder + binder → mixing → granulation → injection molding → degreasing (MIM debinding furnace) → sintering (MIM sintering furnace) → subsequent processing → formed products. In the process of producing MIM cemented carbide parts, improper material selection and operation control in any link may cause defects in cemented carbide parts, so how to avoid such defects?
1. Powder selection link. MIM cemented carbide powder metallurgy not only needs to meet its basic requirements such as particle size distribution and particle size, but also requires high purity powder, and powder with impurities cannot be selected. If the powder contains elements such as sulfur, phosphorus, and silicon, These substances will form pores during the sintering process, resulting in product defects.
2. The production link of feeding. Cemented carbide powder needs a suitable binder during mixing. The cemented carbide powder and binder are fully mixed during mixing. The temperature must be strictly controlled during the mixing process to avoid volatilization and uneven distribution of the binder. , so that the mixed material has good rheological properties and viscosity value after being made into feed, so as to avoid defects in the subsequent links.
3. The link of forming green body. This is also a key link in the production of cemented carbide parts. To avoid product defects, it is necessary to pay attention to the reasonable control of mold temperature, feeding amount, injection pressure, holding pressure, holding time, injection speed, etc. during the injection process, which can be effective Avoid the defects of injection green body.
4. Degreasing link. For the degreasing of cemented carbide green body, in the degreasing process, if the degreasing furnace heats up too fast, it will cause crack defects in the cemented carbide parts, and the degreasing method can be carried out by increasing the temperature step by step.
5. Sintering link. Cemented carbide has a high density, and the product is prone to deformation due to its own gravity during liquid phase sintering. Appropriate support devices can be used. For larger products, materials with comparable shrinkage can be selected as support plates. In addition, the liquid phase sintering time should be shortened as much as possible. 

Detection Systems