Powder Metallurgy

Hello again!

Today’s post is about a modern manufacturing process that goes by the name of Powder Metallurgy.

What is Powder Metallurgy?

žPowder Metallurgy is the process of blending fine powdered materials, pressing them into a desired shape or form (compacting), and then heating the compressed material in a controlled atmosphere to bond and form the material (sintering and presintering) such that the final component usually does not require further machining processes.

žPowder metallurgy became widely recognized after 1945 and today, parts which cannot be formed using other processes are made using this process.

So can any material be processed by this procedure? Well, no. There are 2 main requirements of any material for it to be processed by powder metallurgy:

1.The metal in the powder form must be able to be shaped at high temperature by molecular cohesion.

2.The metal powder must be capable of sufficiently close packing under pressure to permit welding to take place and in case of alloys, be capable of being sufficiently and intimately mixed.

Here are some products that are actually made by powder metallurgy :

pm

https://i0.wp.com/www.ridgwaypm.com/images/miscellaneous-pm-parts-large.jpg

  • žPorous products like bearings and filters.
  • žRefractory parts made from tungsten and molybdenum used in electric bulbs and radio valves, x ray tubes ,etc
  • žProducts of complex shapes like gears which need complex machining when made by other processes.
  • žAutomotive components like electrical contacts , crankshafts,camshafts, piston rings , brackets, brake linings, connecting rods ,etc.
  • žProducts from materials that are very difficult to machine like tungsten carbide , etc Components are gauges , wire drawing dies, wire guides , deep drawing, stamping and blanking tools stone hammers, rock drilling bits.
  • žTungsten parts used in high temperature operations like nozzles for rockets and missiles.
  • Grinding wheels, clocks and other timing devices

So here is the basic processing procedure for making products by Powder Metallurgy :

pm2

  1. The first step is to mix the various powders and lubricants in the required ratio and to ensure the formation of a homogenous mixture.
  2. The next step is to press the component into  the required shape within a specially designed die or press. The component attains its final shape at this stage, but is still very brittle and can break apart at any stage. The powder pressing cycle is shown below.
  3. pressingAfter this stage, the shaped object is sent into a oven for the sintering process.
  4. žSintering is done to achieve the maximum possible hardness and strength needed in the final product.ž Sintering is usually done at 70- 80% of the metal’s melting temperature in an inert atmosphere of hydrogen, ammonia or other hydrocarbons.ž The sintering time varies from thirty minutes to several hours depending on the metal used. Sintering causes the bonding of the solid particles within the component. Once cooled, the powder bonds to form a solid piece.sintering
  5. The final component thus obtained from sintering is allowed to cool down gradually after which it is sent for secondary processes, if required. These may include machining, surface finishing or joining processes.

The advantages of this manufacturing process over other processes include 99% utillisation of material, cleaner and quieter operation, ease of process automation, greater accuracies and quicker manufacturing of complex objects at a high production rate.

The disadvantages of this process are over-dependency on sintering, product size constrains, material constrains, high die design/manufacturing cost and its impracticality for small scale production.

Alright guys, thanks for reading this! Hope this was helpful!

Until next time.

Advertisements

One thought on “Powder Metallurgy

  1. Wonder fully well explained, complex subject with diagrams ,picture ,in ‘simple comman an’s understanding.
    Very useful to new entrant in to business of supply to original equipment manufacturers( OEM),particularly Auto/ Agri/Lighting source ….in small & medium enterprise ( SME), on which our present industisl sector’s & the Govt are laying high importance.
    Many more such articsls will be a boon to SME sector in Emerging markets of Asea.

    Plees keep up Mr. C.S. Sonawala.
    I will be delighted to continue reading ,& contributing write up from time to time.

    Liked by 1 person

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s