Powder Components

The largest field of application for iron and metal powders is component manufacture. Instead of traditional fabrication techniques like forging, casting and machining, iron powder is compacted under very high pressure in a die. The component is then sintered (heat-treated) to give it the requisite mechanical strength. This method is cheaper, especially for long production runs, and it produces components of uniformly excellent quality. In addition, production of sintered powder components consumes much less energy.

Who uses sintered components?

The automotive industry has been using powder components since the 1940s, but it is only in the past ten years that powder metallurgy (PM) technology has begun to replace other methods of fabrication on a significant scale. The annual growth of PM technology in those ten years has exceeded 6 per cent.

A typical modern car contains between seven to fifteen kilograms of powder components. Leading manufacturers predict that the amount will double in the next ten years. The potential is estimated at something like 40 kg per car.

In addition to vehicles, components made of iron powder are used in the manufacture of household appliances, computers, power tools, etc.

Sintered components

The forming of a sintered component begins with the densification of the metal powder in a rigid die having a cavity of more or less complicated contour. In this operation, high pressures (usually 650 N/mm2) are exerted upon the powder in the die cavity, simultaneously from top and bottom, via two or more vertically moving compacting punches.

Under the influence of such high compacting pressures, the powder particles are being squeezed together so that their surface irregularities interlock and a certain amount of cold welding takes place between their surfaces.

After ejection from the die, if the compacting operation was successful, the compact owns sufficient strength (so-called green-strength) to withstand further handling without damage. In order to facilitate the compacting operation and reduce tool-wear to a minimum, a lubricant is admixed to the powder before compacting.

Following compaction the compacts are sintered to give the desired physical properties. The sintering process is governed by the following parameters:

• temperature and time;

• geometrical structure of the powder particles;

• composition of the powder mix;

• density of the powder compact;

• composition of the protective atmosphere in the sintering furnace.

Unique Höganäs powders

Höganäs currently produces 30-odd grades of metal powder for component manufacture, each developed to satisfy the specific needs and requirements of our customers. Typical demands from engine and gearbox manufacturers are low production cost, high strength, durability and corrosion resistance.

Being able to control the size, shape and composition of the powder particles, we can produce metal powders for very specific purposes. One example is Höganäs Distaloy', a product in which alloying elements (copper and nickel) are thermally "glued" to each particle of iron powder. That way we help our customers to avoid the problem of segregation, i.e. migration of heavy particles to the bottom of the container.

Additives are another important factor in improving the functionality of iron powder. Lubricants like Kenolube facilitate the manufacturing process, while additives like MnX' improve machinability.

Höganäs' comprehensive range of metal powders and additives is unique on the world market.