MDM MIM & Metal Casting: Engineering Excellence in Metal Forming

MDM Metal: MIM & Precision Casting Technologies

Metal Injection Molding (MIM)

Metal Injection Molding (MIM) is a metal forming process that involves injecting a plasticized mixture of metal powder and a binder into a mold. The process begins with mixing selected metal powders with a binder, followed by granulation of the mixture and injection molding into the desired shape.

MDM MIM Process Flow

Combining the design flexibility of plastic injection molding with the high strength and integrity of precision metals, MIM delivers a cost-effective solution for manufacturing components with extremely complex geometries. The MDM MIM process consists of four distinct steps—Mixing, Molding, Debinding, Sintering—with surface treatment added as an optional step based on product requirements.

MDM Metal MIM Mixing

Fine metal powders are blended with thermoplastic and paraffin binders in a precise ratio. Mixing is conducted in a specialized device, with heating to melt the binder. Mechanical mixing is used in most cases until metal powder particles are uniformly coated with the binder. The mixture is then cooled to form pellets (called feedstock), which can be injected into mold cavities.

MDM Metal MIM Molding

MDM adopts injection molding equipment and technology similar to plastic injection molding. Pelletized feedstock is fed into the machine, heated, and injected into mold cavities under high pressure to form green parts, which are demolded after cooling. This entire process requires the binder to melt at approximately 200°C for full integration with metal powders. Molds can be designed with multiple cavities to boost productivity, and their dimensions account for the shrinkage of metal components during sintering—with precise, known shrinkage rates for each material.

MDM Metal MIM Debinding

Debinding is the process of removing the binder from molded green parts, typically completed in several steps. The vast majority of the binder is removed before sintering, with a small residue left to support the part during transfer to the sintering furnace.Solvent extraction is the most commonly used debinding method. Debound parts become semi-permeable, allowing residual binder to be easily vaporized during sintering.

MDM Metal MIM Sintering

Debound parts are placed in a furnace with precise high-temperature and high-pressure control, and slowly heated in a protective gas atmosphere to remove residual binder. Once the binder is completely eliminated, the part is heated to a high temperature, at which the gaps between powder particles disappear due to particle fusion. The part shrinks directionally to its designed dimensions and transforms into a dense solid. For most materials, the typical sintered density reaches over 97% of the theoretical density, resulting in product performance comparable to forged materials.

MDM Metal MIM Surface Treatment

Some parts may require surface treatment after sintering based on specific needs. Heat treatment enhances the physical properties of metals; electroplating and painting are applicable to high-density materials. MDM also provides welding and cooling treatment technologies as post-sintering processes.

Key Characteristics of MDM MIM Products

As a professional MIM manufacturer in Shenzhen, MDM Metal’s MIM products feature the following core attributes:

Design Complexity

Like plastic injection molding, MIM has no restrictions on shape design. As an integral forming process, adding product features does not increase costs, making MIM an ideal solution for integrating individual parts into multi-functional components. MIM design rules are highly similar to those of plastic injection molding, enabling its application for almost all products.

High Precision

The typical net-shape precision of MIM is ±0.5% of the dimension, with some features achievable to ±0.3% net-shape. As with other manufacturing technologies, higher precision requirements lead to higher costs—thus, moderate tolerance relaxation is recommended where quality permits. Tolerances unachievable via one-step MIM forming can be realized through subsequent surface treatment.

Weight & Dimensions

MIM is particularly suitable for components weighing less than 100 grams, with parts under 50 grams being the most cost-effective. However, components up to 250 grams can also be processed. Raw materials represent the main cost of the MIM process, so MDM leverages advanced technologies to minimize component weight. Similar to plastic products, weight reduction is achievable via internal cores and supporting structures without compromising product integrity. MIM excels in manufacturing micro and miniature components (even under 0.1 grams) and is not limited by length—products over 250 mm in length can be processed.

Wall Thickness

A wall thickness of less than 6 mm is optimal for MIM. Thicker outer walls are feasible but increase costs due to longer processing times and additional material usage. Ultra-thin walls of less than 0.5 mm can also be achieved with MIM, though they impose stringent design requirements.

Production Volume

MIM is a highly flexible process, enabling cost-effective production for annual demand ranging from several thousand to millions of pieces. Like cast and injection-molded parts, MIM requires customer investment in mold and tooling costs, which typically impacts cost estimates for small-batch production.

Material Compatibility

MIM processes a wide range of materials, including iron alloys, superalloys, titanium alloys, copper alloys, refractory metals, cemented carbides, ceramics, and metal matrix composites. While non-ferrous alloys such as aluminum and copper are technically feasible for MIM, they are usually processed via more cost-effective methods such as die casting or machining.

MIM Design Guidelines & Applications

MDM MIM technology is widely used in the automotive, medical, electronics, industrial, and consumer goods industries. Its applications cover automotive parts, aerospace equipment, mobile phones, dental instruments, electronic heat sinks and hermetic packages, electronic connector hardware, industrial tools, fiber optic connectors, spray systems, disk drives, medical devices,colorimters， handheld power tools, surgical instruments, and sporting goods.

MDM Metal Precision Casting

Precision casting is a special casting method compared with traditional casting processes, capable of producing castings with relatively accurate shapes and high dimensional precision. Its general process flow is as follows: design and manufacture a mold with minimal or no machining allowance according to product requirements; cast wax to create the original wax pattern; repeat coating and sanding on the wax pattern to harden and dry the mold shell; melt and remove the internal wax pattern (dewaxing) to form the mold cavity; fire the mold shell to achieve sufficient strength and air permeability; pour the required metal material; remove the shell, clean sand, cut and grind gates to obtain high-precision finished products. Post-processing includes sandblasting, shot peening, correction, and pickling.

Stainless Steel Precision Casting Process Flow

Wax Injection → Mold Shell Making → Dewaxing → Mold Shell Firing → Pouring → Shell Shaking & Sand Cleaning → Cutting & Grinding → Inspection & Packaging

Key Features of MDM Precision Casting

Compared with other casting and part forming methods, MDM’s precision casting offers the following advantages:

High Dimensional Precision

Casting dimensional accuracy reaches Grade 4–6: ±0.13 mm for 20 mm parts, ±0.30 mm for 100 mm parts, ±0.43 mm for 200 mm parts (precision for small parts is hard to reach within ±0.10 mm). The angular tolerance is 0.5°–±2.0°, and the minimum wall thickness of castings can be 0.5 mm. The surface roughness is as low as Rmax-12S, greatly reducing machining allowance and enabling near-net-shape casting.

Unrestricted Material Selection

Casting materials are customizable, including stainless steel, alloy steel, carbon steel, etc. Material compositions can be formulated on demand to meet engineering requirements for rust resistance, hardness, surface finish, and mechanical properties.

Complex Shape Capability

Precision casting can produce products with complex geometries that cannot be formed by other processing methods.

High Production Flexibility & Adaptability

It is suitable for both mass and small-batch production, and supports repeated multi-batch manufacturing.

About MDM Metal

MDM Metal is a leading metal powder injection molding (MIM) company in China and one of the global MIM professional enterprises. MDM is based on manufacturing, extends materials, and integrates technology to create six core product systems: precision structural components, automotive plastic components, power, thermal energy, ODM, and intelligent manufacturing. It has been widely used in consumer electronics, automotive, medical, smart home, new energy, and other fields, and works together with global users to create a better life.