Metal Injection Molding

Inox Cast Metal Injection Molding

Inox Cast is an expertise-driven manufacturer that is committed to giving customers with premier services. We are offering a complete solution so we can help you in skyrocketing your business and project.

We specializes in offering metal injection molding services for more than 20 years. Here in Inox Cast, we can surely provide your metal injection molding requirements for your applications and special needs. Inox Cast is surely your trusted manufacturer.

Inox Cast focuses on metal injection molding for metal forming processes. It combines powder metallurgy and injection forming techniques. The metal injection molding can be injected to produce components with different complex shapes.

Advantages of Inox Cast Metal Injection Molding

• It can process a variety of materials such as stainless steel, nickel-cobalt alloy, chrome-molybdenum alloy, and more.
• It is perfect for complex part shapes. Through our excellent injection process, we can produce complex parts with complex shapes.
• It has a high strength. We can guarantee you up to 95% high strength than normal.
• Metal Injection Molding parts are ideal for component mass production
• It helps in minimizing production cost since it can omit contour machining.
• It is widely used in different industries like tool industry, defense industry, communication, consumer, computer, aerospace, and more.

The structural designs of our metal injection moldings have conformed to economy and rationality of the processing. We are a manufacturer that integrates optimization, formulation, and process selection.

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Metal Injection Molding: The Ultimate FAQ Guide

In this guide, you will find all information you are looking for about metal injection Molding.

Whether you want to learn about the process, specification, applications or design characteristics, you will find all information right here.

So, keep reading to learn more.

What Is Metal Injection Molding?

A metalworking process where binder material is mixed with finely-powdered metal to create a feedstock is called Metal Injection Molding.

Shape and solidify the feedstock using injection molding process to allow a single step shaping of high volume complex parts.

metal injection moulding

Why Choose Metal Injection Molding?

• It has freedom to manufacture complicated shapes that would be considered cost prohibitive by other methods.
• It manufactures micro-sized parts in high volumes.
• Net shaped features are achieved e.g. internal and external threads, profiled holes, finely detailed surface textures, knurling, engravings and markings.
• It joins MPP material to a variety of component for a complete assembly solutions.
• They formulate tailored solutions using unique materials hence meeting components requirement.
• When it comes to finishes, their surfaces have excellent finishing.
• Mechanical properties of MIM are excellent.

What Are The Limitations Of Metal Injection Molding?

• In metal injection molding process high initial investment is required due to tool manufacturing thus higher initial cost.
• It is not possible to manufacture parts of more than 20cm in MIM process unlike small parts.
• MIM is suitable in higher quantities only.

How Does Metal Injection Molding Compare To Metal Die Casting Process?

Metal die casting raw materials are aluminum alloy and zinc alloy while metal injection molding uses steel or other types of MIM alloys.

Metal die casting offers large cost savings opportunities for the component designer unlike MIM.

When it comes to forming high volumes of net-shape components the fastest and most economical way is die casting process.

metal injection moulding

Zinc mixed with aluminum, copper and magnesium into an ingot shipped to die casting facility is a process called zinc alloying.

Melt the ingot in a central furnace at the die casting plant and transport it to the die casting machine.

In hot chamber die casting process immerse the pump in the molten alloy.

Then push the alloy through the die casting machine and into a die.

In MIM process, formation of the metal alloy into a fine powder mixed with a thermoplastic binder to form a feed stock.

Ship the feed stock from the supplier to the injection molding plant and heat, inject into a mold, cool and then eject from the mold.

Higher strength components are produced in MIM Process as compared to die casting process.

Metal die casting

Metal Injection Molding process is much more costly than the die casting process which is 30% less expensive.

Is There Difference Between Metal Injection Molding And Plastic Injection Molding?

Yes, there are differences.

Metal Injection Molding is a process that involve metal parts.

Plastic Injection Molding is a process that involves plastics and rubber parts.

In MIM proper amount of binder is mixed with metal powder and made into feedstock to use in conventional molding machine.

plastic injection moulding

In Plastic Injection Molding plastic pellets are heated and melted, in molding machine the molten plastic is injected into the mold.

How Does Injection Metal Molding Process Work?

Preparation Of  Feedstock For Metal Injection Molding

Create a powder mixture of polymer and metal.

Use under 20 microns powder metal which are very fine than those in traditional powder metallurgy processes.

Mix a hot thermoplastic binder with the powder metal, cool and then granulate into a homogenous feedstock in pellets form.

This process results to 60% metal and 40% polymer by volume.

Injection Molding

Using plastic injection molding equipment and tooling mold the powder feedstock.

Design approximately 20% larger mold cavities to account for the part shrinkage during sintering.

Melt the feedstock and inject into mold cavity, then cool and solidify in the shape of injection molding cycle part.

Clean and eject the molded green part to remove all flash.

MIM Debinding

The process of removing polymer binder from the metal is called debinding.

Place green part in a water or chemical bath to dissolve the binder solvent.

Perform thermal debinding by heating green part in a low temperature oven.

Via evaporation remove polymer binder leaving a brown metal part with approximate content of 40% empty space by volume.

MIM Sintering

Sinter the brown part in a high temperature furnace up to 2500°F thus reducing empty space hence high-density metal part.

Pores from the material are removed by MIM sintering process causing uniform shrinkage of the part which can be predicted accurately.

The original molded shape with high tolerances and with much greater density part is retained.

What Should You Consider When Designing Metal Injection Molding Components?

-Gate location and gating

Depending on the geometry of the part design we may have a single gate or multiple gates.

Parting Lines and parting line witness

To mold component, parting lines are essential.

Keep in mind application of whether parting line on geometry impacts the form, fit and function of the part or not.

Avoid parting line on the functional surface.

-Ejector Marks

Eject all parts from the mold.

To minimize ejector marks you will have to utilize sleeve ejection.

-Thickness of the wall and Features

Consider injecting thin wall features e.g. 0.020 or less in a mold.

If it’s not ejected properly the risks that features can break off in a green state are high.

-Drag Effect

The fact that inherent to the MIM process during the sintering stage is drag effect.

A part shrinks on the tiles when we put into sintering oven.

Averagely a MIM part will shrink about 20 percent, grade of the material will determine the specific shrinking rates.

-Sag Effect

During the sintering process the sag effect occurs.

Parts become soft and tend to run or sag due to unsupported features, cantilevers or gravity.

Create a design that counters the effects of gravity for sag effect design.

In order to maintain unsupported features, add special centers or ceramics that are individual blocks or custom machine ceramics.

-Draft Angles

When pulling mold in high aspect ratio features as a thin wall section or long core pin we require draft angle.

For additional relief introduce a half-a-degree draft.

In some cases wax in paraffin wax in the feedstock acts as a mold release agent.

This acts in place of draft angle allowing us have most part and straight holes in the mold with little shrinkage.

-Wall Thickness

You must have uniform wall thickness.

This control the shrinkage variability hence an ideal MIM part.

-Undercuts

To reduce the need for a secondary operation and cost we mold in undercuts with collapsible core design.

It is easy to produce internal and external Undercuts.

All Metals Suitable For Injection Molding?

• Low alloy steels

Have high wear and strength resistivity properties.

They offer good magnetic property.

• Stainless steels

When fully hardened they provide maximum corrosion resistance.

Their edge retention and wear resistance are excellent.

Are easy to machine.

• High-speed steels

Are excellent in hardness and abrasion resistance.

They trade for toughness, reduced brittleness and hot hardness with different grades.

• Irons

Have high electrical resistivity and they also exhibits low core losses.

They have high permeability properties.

• Cobalt alloys

Excellent wear and corrosion resistance.

Have high temperature strength.

Their magnetic properties are excellent.

• Copper alloys

They have high thermal conductivity.

Are high in resisting corrosion.

Easy machinability.

• Tungsten alloys

They have high strength and thermal conductivity properties.

Have high density and high melting point properties.

• Titanium alloys

Even at extreme temperatures they exhibit high tensile and toughness properties.

Their corrosion resistivity is very high.

Are light weight.

• Nickel alloys

Is There Recommended Tolerance For Metal Injection Molding?

Yes.

+0.3%-+0.5%  is the tolerance range for MIM process.

It will differ depending on factors like location of injection point, material used, thermal treatment and the shape of the part.

Which Secondary Operations Can You Apply On Metal Injection Molding Parts?

• Cold deformation  or Coining

Force a sintered component to conform to a rigid mandrel or substrate so as to straighten and ensure desired flatness and dimensions.

This will allow features with a reduced spread in dimensions to size properly.

•  Hot deformation

Heat sintered component and deform it by a rapid forging stoke ensuring proper size and density.

The sintered strength of steel after hot deforming will jumps from 500 MPa to 720 MPa.

• Machining

Apply all common machining operations to sintered MIM components.
In the tooling add threads, grooves, undercuts, ultra-tight tolerances, special features difficult or expensive.

• Heat treatment

Adjust hardness and other properties for high carbon levels using heat treatment.

Into the sintering cooling cycle incorporate the heat treatment.

Precipitate the hardened stainless steels to optimize the mechanical properties properly.

• Hot Isostatic Press

Sintered MIM parts are 98 – 99% dense.

Load the components into a sealed chamber

Introduce argon gas and heat the chamber creating pressure which compresses the parts and collapses residual internal porosity.

• Surface carburization

Attain high surface hardness by adding carbon surface using a heating cycle with an atmosphere containing methane.

For dimensional accuracy we require trade-off between surface hardness due to the addition of carbon hence high dimensional precision.

• Joining

Join MIM components by welding, brazing or adhesive techniques.

• Surface treatments

Apply surface treatments to MIM components e.g. polishing, coating, anodizing, plating, sealing etc.

Hard surface has a tough core to sustain surface hardening treatments.

Use electroplating to improve either aesthetics or corrosion resistance.

What Are The Main Metal Injection Molding Applications?

• Widely used in automotive components industries
• Are used in computers, office products and home appliance components
• In fittings and Ornaments
• For medical equipment and other precision instrument components
• Used in soft magnetic components

How Do You Choose Metal Injection Molding Machine?

• Mass/volume
  MIM reduces fabrication costs for components where much material loss would occur in machining or grinding.
• Quantity
  Low production quantities tooling and set-up costs are difficult to justify, MIM works best when annual production quantities exceed 20,000 yearly.
• Material
  Get a machine that can manage materials like titanium, stainless steel and nickel alloys which are very hard to machine.
• Complexity
  MIM works best for indexing machining on components that require multiple axes.
• Performance
  MIM generates competitive properties due to its high density.
• Surface finish
  The initial particle size is reflected by the surface roughness where controlling textures is possible at almost no cost penalty.
• Tolerances
  With tight tolerances MIM have a high cost from secondary operations with as-sintered tolerances of ± 0.3%
• Assembly
  To save on inventory and assembly costs consolidate multiple parts into a single piece.
• Blemishes
  In MIM blemishes like gates marks, ejector pin marks and parting lines are located in noncritical positions or removed after fabrication.
• Novel compositions
  MIM forms novel material combinations like laminated or mixed metal-ceramic materials for wear applications which are difficult via traditional processes.

Is Metal Injection Molding Same As Metal Sintering?

• MIM offers a superior magnetic performance.
• In need of assembly MIM produces one part unlike metal sintering processes which will produce two components.
• MIM offers a part with a superior density compared to the ones produced when using conventional processes.
• Corrosion performance is excellent in MIM than in conventional metal sintered parts.
• MIM parts have a superior strength and ductility compared to parts being produced with conventional powder metallurgy process.

Metal sintering

Is Metal Injection Molding Suitable For Complex Parts?

Yes, This is because manufacturing of complex parts is simplified by MIM.

It is efficient in fabrication of complex components.

Has intricate surface and custom textures making it able to produce highly complex components.

Is Metal Injection Molding Same As Powder Metallurgy?

MIM creates a high level of complex geometries that PM can’t.

MIM uses relatively low pressure slurry thus forming more complex geometries whereas PM uses high pressure compacting powder columns to shape.

MIM use components like undercuts, severe draft angles, surface features while PM only needs straight walls.

powder metallugry

How Do You Determine Cost Of Metal Injection Molding Cost?

-Mold Life
Product life time determines mold life time thus total order quantities during the life time.
Tooling cost is affected mainly by mold life.

We require molds at higher volume and hardened steel like NAK 80 or H13.-Complexity of the parts
Complexity adds extra work to machining and more steps during molding manufacturing.
Re-design your parts to a simplified version hence lower molding costs.
-Molding Materials
Plastic molding material you select affects the cost of tools and piece pricing which varies from different types of materials.
-Surface Finish
Type of finishing you choose determines how much the product costs.

Mirror polishing requires hardened steels like NAK 80 Steel to create the molds thus adds cost to injection molding.

The higher the texture the higher the cost.

-Part size

When the size of the part is big the gap between the costs of 250,000-3million pieces is small.

What Is The Difference Between Metal Injection Molding And Powder Injection Molding?

In MIM the parts are uniform all through.

While in Powder Injection Molding the final component is not uniform because of the friction between the powder and tooling.

MIM process is expensive and needs more energy in making smaller size range of powder used.

In PIM coarser powder which are widely known are used hence less expensive.

What Are The Unique Attributes Of MIM Process?

• They are repeatable process for high-temperature alloys complex components.
• MIM parts provides excellent mechanical, magnetic, corrosion, and hermetic sealing properties due to their nearly fully dense properties.

They allow secondary operations like plating, heat treating and machining to be performed easily.

• Achieve complex shapes through innovative tooling techniques similar to those used in the plastic injection molding industry.
• MIM attains high volumes through multi-cavity tooling.

What Are The Design Rules In MIM?

• Thickness of the wall

Keep the wall thickness uniform and minimized throughout the part just as with plastic injection molding.

Minimize wall thickness to reduce material volume and cycle time thus reducing debinding and sintering times.

• Draft

In MIM parts do not require drafts unlike in plastic injection molding.

The mold releases the polymer binder used in the powder material more easily than most injection molded polymers.

Eject MIM parts before fully cooling and shrinking around the mold features because the metal powder in the mixture takes longer to cool.

• Sintering support

Support MIM parts properly to avoid distortion when shrinking during sintering.

Use standard flat support trays to design parts with flat surfaces on the same plane to avoid expensive custom supports.

Which Characteristics Should You Look For In Metal Injection Molding Products?

-Precision

The net shape feature precision of MIM is ± 0.5% of the dimension.

When precision is high the cost is high thus encouraging relaxation of tolerances.

-Complexity

In MIM same design freedom as plastic injection molding which gives almost limitless shape capability is allowed.

MIM molding process is ideal for combining individual parts into multi-functional products thus has no variation in cost.

MIM adapts to almost any product due to design rules which are very close to that of plastic injection molding.

-Size and Weight

Parts weighing less than 100 grams with most economical applications being less than 50 grams is suitable in MIM.

For MIM process raw material is a key cost driver.

Without compromising product integrity MIM promotes creative ways to reduce part weight wherever possible.

MIM excels at extremely small and micro-sized parts with possible weights of less than 0.1 gram.

In excess product lengths of 250 mm can be processed.

-Section Thickness

Less than 6 mm wall sections are most appropriate for the MIM process.

When it comes to thicker sections longer processing times and additional material are required thus high costs.

Less than 0.5 mm thin sections are possible for MIM to achieve but are highly design dependent.

-Production Volumes

Several thousand parts annually to millions of parts can be economically achieved in MIM due to its highly scalable process.

To drive the decision process for low volume products for MIM process, tooling and engineering investment is necessary.

-Materials

A wide array of materials e.g. Ferrous alloys, Cobalt base super alloys, Titanium alloys, Nickel and Technical ceramics are processed by MIM.

While Aluminum and Copper alloys which are non-ferrous alloys are technically possible.

They are processed more economically by die casting or machining means.

Other material processing technique you may be interested in include die casting and injection molding.

For any questions or inquiry on metal injection molding, contact us now.