The standard of choosing powder metallurgy
2015-10-16
1.Products size
The size of powder metallurgy parts is limited by the compressibility of powder and tons of compacting machine.For normal steel powder metallurgy material,can create following spec.of parts:
Projection surface area lower than 32 000ram2
Diameter less than 170mm or max 300ram(for parts with big hole)
Maxlength 150ram,minlength 1.5ram
The max ratio between length and diameter is 5:1;the max ratio between length and wall thickness is 8
If the design of products are using non-iron metal material,the projection area can increase 50%
2.Products shape
The products geometry must be suitable to make uniaxial press in in vertical.direction.Undercut,recess or thread are normally finished by post process or machining.When the cross section of parts changes a lot,it requires the tooling on molding machine has various action.These limited components can only have 5 flats,but,through tooling design,adding small alteration in the length of parts direction is possible.When the length of parts are longer than 25.4mm,the density will be different from top(max density) to middle(relatively low).
3.Products quantity
Considering the special tooling is “hardware”,so it is necessary to discuss the purchase order quantity or MOQ.
4.Mechanics/Physical property requirements
In order to help most of products to choose suitable material,spec.35 provides widely design performance.The number of medium-density steel(6．4-6．9g／cm3) can replace cast iron or plain carbon steel;high-density brand(7．0～7．4g／em3) can replace toughness ductile iron or heat-treated iron;powder forging and non-porous material can replace high-performance steel.If the key property of products design must be beyond the standard value of standard,then these requirements must be listed on the drawing.
In order to choose the best material in performance,cost and feasibility,it is very important to discuss the application of products with customer,In order to avoid concepts unclear or misunderstanding,customer and supplier should reach an agreement before producing powder metallurgy products.like min strength,brand of material,chemical composition,inspection test,standard property value and producing tech,as these factors will influence the function of products.
5.Products usage
The products tech.spec. or drawing should provide additional information as clear as possible,also provide assembling picture to supplier to let them fully understand the application of products.For choosing material and producing process,following questions are very important:
When products work under fluid pressure,are they required sealed and no leakage?
When products are required to prevent erosion,what’s the standard?
Which area are required machining?What’s the tolerance?
What kind of heat treatment required?
Are the products used in high-impact load?
If the products require anti-wear function,which face requires?
Surface roughness is a very important design,which face requires this?And how to measure?
Are the products used in magnetic applications?
Are the products used in high temperature environment ?
What kind of burrs does the product not allowed to have?Fillet radius size?
Does the product require welding?
For the usage function of product,does it has requirement for critical location?
Does product require special package?
