Flow Marks in Powder Injection Molding

Powder injection molding manufacture notes flow marks  is a common defect in MIM process. Let’ probe into the reason for flow marks defect based on past MIM parts experience.

Phenomenon:

The initial injected feedstock cool down rapidly, then generate interface with later injected feedstock, the flow marks refers to injection gate centered concentric circles mark.

The causes and treatment:
- the mold temperature is too low
- injection speed is too slow
-poor liquidity of raw material
- too small injection gate
-too low or uneven temperature for mould and feedstock
- no cold slug well or too small
-poor  product design,  thickness change big .

Original article link：http://www.zcmim.com/article/flowmarksinpowderinjectionmolding_1.html

Crazing Defect in MIM Process

Powder injection molding manufacture notes crazing  is a common defect in MIM process. Let’ probe into the reason for crazing defect based on past MIM parts experience.

When feedstock flows in mould,  the material near mould wall cool down faster than central hot melt interface, which will form shear stress for the central  hot melt interface, therefore crack occurs .

The causes and treatment:
- low quality mould , draft angle is insufficient
- too strong injection pressure or holding time is too long
- mold temperature is too low
- finished products cling to mould surface in vacuum status
- bad inserts design, or temperature is too low
- poor finished product design, change thickness greatly or  acute Angle

Original article link：http://www.zcmim.com/article/crazingdefectinmimprocess_1.html

Surface Treatment for Metal Injection Molding Robotic Components

The very common surface process for MIM (metal injection molding)

 rc helicopter drone parts is magnetic grinding. It is processed by magnetic grinding machine and needle, mixing brightening agent and water. Put products on grinding machine plate for grinding 20-40 minutes. The grinding time is subject to the requirements of brightness.

Another common surface finish for MIM robotic parts are sandblasting. It is processed by sandblasting machine.

There are two kinds sandblasting machines: automatic and manual. Adhering required sands to product surface by Pneumatic nozzle. The pressure is usually 3 kg, keeping for 10 minutes .At same time it can chose fine or rough sands according to different requirements.

What UAV&Drone Parts can be Manufactured by MIM Process

Drone shaft, remote control buttons and spindle are all can be made by metalinjection molding MIM. After sintering, the products will make several tests like tensile strength test, impact toughness test, bending test. Compared with traditional PM process, The MIM parts have great advantages in mechanical properties, surface quality, shape complexity, material utilization, as well as production efficiency.

Void in MIM Smartphone Lens Ring

MIM process manufacture notes that void is a common defect in MIM process. Looking at the reason for void based on our last experience of UAV remote control metal button project.

There are two reasons for inner space within finish products:

1. Occurred in thick part, resulting from contraction after central cooling
2. Caused by volatile decomposition of plastic, air or water

The causes and treatment:
-  injection pressure is too low, holding time is too short.

- the back pressure is too low
- material temperature is too high, sticking for too long time
- improper design of product thickness
- mould flow channel or injection gate is too small

 --don’t dry material enough

- spray too much mold release agent 

Weld Line in MIM Smartphone Lens Ring

MIM process manufacture notes that weld line is a common defect in MIM process. Looking at the reason for weld line based on our last experience of UAV remote control metal button project.

Weld line refers to the junction lines left in wave front when material flow into mould.

 
The causes and treatment:
- the temperature of mould or material is too low

- pressure is too low or insufficient shooting speed

- illiquidity material
- improper design for product thickness

- mould flow channel or injection gate is too small
- bad exhaust channel

- spray too much mold release agent

How is the binder classified?

A practical binder is generally composed of several components, each group has its own unique function, according to the function can be divided into main binder, secondary binder and additives. According to the principal components and properties of the binder system, the binder system can be divided into thermoplastic binder, thermosetting binder, gel system, water soluble binder and special system.

Among them, thermoplastic binder is the most widely used, and is divided into paraffin based binder, oil based binder, polymer based binder, etc..

Thermoplastic adhesives are generally made of high molecular polymer, low molecular weight substances, and the necessary additives (such as paraffin base binder, oil based binder, etc.). The functions of each component are as follows:

Polymer: high viscosity, high strength, in the process of injection and skim to maintain the shape of the billet

Low molecular weight material: low viscosity, good fluidity, can be removed at lower temperature in the process of low temperature, leaving a gap in the blank, which is conducive to the late fast hot melt

Additive: to improve the stress, reduce the viscosity, increase the wettability or lubrication.

MIM how to select binder?

Binder is the core of MIM technology, and MIM is an important difference compared with conventional powder metallurgy method. The main function of the binder is to act as a carrier for the flow of the bonded metal powder particles and to maintain the shape of the workpiece.

MIM binder should meet the following requirements:

The contact angle of the powder is small, and the adhesion ability is strong, and the reaction is not with the powder;

Injection temperature range of viscosity change is not big, but the cooling viscosity change fast

Non stick mould;

With less dosage, the mixture can produce better rheological properties with less binder;

The effect of copper powder metallurgy

In the field of powder metallurgy, pure copper and thermal production of electronic components. Copper alloys containing tin, zinc, nickel, or iron are widely used in automotive, lawn park equipment, tools, and electronics industries. Copper is most widely used in self lubricating bearings, the other is Fe-Cu premix, chemical industrial areas of dialysis and friction materials.

The application and characteristics of the copper powder is an important field of powder metallurgy. Materials in this area are not obtained by smelting and casting, and self lubrication bearings and filters are typical applications in the field of powder metallurgy. These materials are required to control the proper porosity and to achieve a good lubricating effect.

Copper powder by metal injection moldingprocess can be made into a complex shape of electrical and electronic components, the product has good electrical conductivity and thermal conductivity. We can use the high pure copper powder, to improve the conductivity and thermal conductivity through the final density of parts. The injection molding process can improve the copper powder density, electrical conductivity and thermal conductivity of products increased.

MIM metal powder summary

Metal injection molding (MIM) is more suitable for small and three-dimensional in charge of the shape of the special products, this process is also a plastic injection molding technology introduced to the powder metallurgy industry. At present, MIM metal powder raw materials, including iron, nickel, titanium, stainless steel, precious metals, alloys and other materials. At the same time more in the development of diversification, such as structural materials, functional materials, magnetic materials, etc..
 The MIM powder production method mainly include: carbonyl and super high-pressure water atomization method, high-pressure gas atomization method, plasma atomization and laminar flow atomization. Different powder preparation techniques have different effects on the size, shape, microstructure, chemical properties and manufacturing cost of the powder.

Australian customers to visit the ZCMIM factory

The product engineer Charles from ORBITKEY came to vist our factory yesterday. We discussed all the details one by one for project at hand and also explain MIM process to Charles, This is the first time for Charles to know MIM, therefore the visit is full of curiosity. He was very satisfied with our engineering, QC and factory atomsphere.

Regarding current discussed project, everything is done except should make a little change for product structure to achieve better surface. Charles said he would be double check for it once back.

Customer web site: www.orbitkey.com

ZCMIM powder metallurgy metal injection molding can be applied to what industry?

specializing in the production of small and complex metal parts, mobile phone metal parts, medical machinery parts, industrial metal parts, such as metal parts, set custom, processing, sales of one-stop service. ZCMIM powder metallurgy metal injection molding can be applied to what industry? With small make up to see it!

1, mobile phone equipment

In fact, there are several parts of the phone is the use of metal injection molding method. For example: the manufacturing tungsten vibrator balance weight, use made of high strength steel hinges, metal injection forming method in mobile phone is one of the most important application is to create a slide, barrel and a hinge.

In addition, due to the need for lighter, thinner and more beautiful mobile phone market and need to use the best technology, reduce their size, a mobile phone company is seeking for metal injection forming method for manufacturing the assembly parts of the mobile phone.

2, medical machinery parts

Metal powder injection molding technology in the processing of medical machinery parts also played a relatively large role. For example, orthopedic rack teeth, scissors, tweezers etc..

3, ordinary household appliances

In addition to the above two industries, the technology can also be used in the manufacture of ordinary household appliances. For example, watchcase, watch chain, electric toothbrush, scissors, fan, golf head, jewelry chain, ball point pen card first hoop, a knife cutting tool parts.

Stainless steel nuts

Stainless steel nut it is to connect the machinery and equipment parts, through the inside of the thread, and the screw tightly connected together. The MIM can do parts of complex structure, relatively small metal parts, there are many miniature nut is made by MIM.

Stainless steel parts nut is nut, bolt or screw rod and together to play of the fastening parts, all production machinery manufacturing must use an original. Nuts are different, we common standard, British standard, American Standard, the standard, the nut. Nut according to different materials, high strength, GB, standard & Poor's, ordinary types. To according to different sizes, thread is not equal for different specifications.

How to polish the stainless steel parts

Polishing is refers to the use of mechanical, chemical or electrochemical and the workpiece surface roughness decreased, to obtain bright and smooth surface processing method is the use of flexible polishing tools and abrasive particles or other polishing media on the workpiece surface modifying and processing.

Methods: deburring, magnetic polishing machine, magnetic abrasive finishing machine. Magnetic deburring is the use of magnetic field strength, guide grinding material fast rotational motion and grinding the workpiece to achieve, to flash (flash), surface polishing, light washing, wash, to film, to mark the sintering, to corrosion, grinding effect.

Complete objective: can make the workpiece surface polishing, polishing bright, smooth; deburring, flying edge, sharp edges, burrs; oxide film; to sintering traces, restore the color of the metal; wash, metal machining scrap, slag; front side of the inverted angle is slippery; to optimize the surface plating, welding; metal surface paint.

What are the advantages of metal powder injection molding technology?

Powder injection molding MIM method has advantages of low cost, high efficiency can be customized processing of any complex small metal hardware accessories, for such a process, also known: the most popular technology of molding parts, then metal powder injection molding technology has what advantage? Following up to look at it.

1, can reduce the alloy component segregation, eliminate the coarse.

2, can be in amorphous and microcrystalline, crystal preparation, nano crystalline, over - saturated solid solution, such as a series of high performance non - balanced materials. These materials have excellent electrical, magnetic, optical and mechanical properties.

3, metal powder injection molding technology can realize the near net shape and automated mass production, can effectively reduce the production of resources and energy consumption.

4. Materials and products with special structure and properties, such as new type porous materials, porous separation membrane materials, high performance ceramic materials and ceramic materials can be produced.

5, can make full use of ore, tailings, steel mills, steel mill scale, recycling of metal waste as raw materials, is a new technology, can effectively carry out the material recycling and comprehensive utilization.

The technique has unique chemical composition and mechanical properties and physical properties, which can not be obtained by conventional casting methods. It can be directly made into porous, semi dense or fully dense materials and products, such as oil bearing, gear, cam, guide rod, knife, etc..

What are the two basic methods used in metal powder injection molding?

In the process of metal powder injection molding, why should we use fine powder as the raw material? Usually, which are the two basic methods of zcmim powder metallurgy factory below for you to answer:

1) small particles, large surface area, the higher the surface, can improve the power of sintering of powder;

2) grain refinement, the increase of the coupling force between the particles, improve the strength of the body after the skim;

3) fine particle resistance, melt and binder in the flow is not easy to separate, easy to mix and injection.

Thermal and solvent are usually used. The solvent debinding in injection molding to form an open pore network and subsequent thermal debinding of decomposition product discharge with mass transfer channel for the decomposition products may form the inner pressure and the chances of debinding defects caused by, degreasing speed.

Pressure sintering and microwave sintering

Pressure sintering of powder pressing billet heating and also the pressure can be obtained than atmospheric firing crystalline particle more fine, more dense sintered body, people commonly used heat pressure, sinter hip sintering preparation high performance stainless steel. The results show that the pressure accelerates the flow and particle rearrangement of the liquid phase, the greater the pressure, the greater the densification rate, and the close to full densification of the stainless steel after hot and so on.

Microwave sintering, which is a kind of fast sintering technology, which is used to realize the densification of the sintered body by sintering temperature and sintering temperature by using the dielectric loss of the material in the microwave electromagnetic field. In sintering process, microwave sintering can quickly jumped over the surface diffusion stage, the grain to not grow up to complete densification and rapid cooling, so it for grains in sintering process control of growing up is a kind of effective method.