Finishing

A Range of Finishing Touches for the Parts We Produce

Our high tech facilities and in-house team of experts enable us to create tools, parts and components for a wide range of clients in the automotive, rail and construction industries, as well as beyond. A large part of the reason why clients like Rolls Royce and Aston Martin have worked with us so many times since we started in 1996 is our incredible attention to detail. As well as offering CNC machining facilities, 5 axis laser cutting and pressing and forming, we provide a wide range of finishes for the components and tools we produce, from the dazzling gleam of Brightware to put the final touch on a prestige motor vehicle to treatments designed to harden components for heavier industrial use. We offer the following types of finishing:

Polishing

Polishing is a relatively simple form of finishing which improves the appearance of a metal by applying an abrasive to the surface. The process works by initially applying a highly abrasive surface and then gradually using finer levels of abrasion in order to develop a rich, deep shine. ‘Cut motion’ is the name of a polishing technique which applies medium to heavy pressure on the metal in order to create a semi-bright finish, while ‘colour motion’ uses lighter pressure to achieve a brighter final polish.

Case Hardening

Case hardening is a form of heat treating which involves applying carbon and nitrogen to the surface of steel parts. Different forms of case hardening include gas or oil carburizing, dry cyaniding, and pack carburising using solid materials like charcoal and coke.

All of the different methods have the same intention – to create an extremely tough central core and a surface which is highly resistant to wear. This is done by increasing the carbon content of the surface to between 0.80% and 1.20%. This creates an extremely tough external case, and the depth of the case can be varied by varying the temperature of the treatment, the time it takes and the carburising medium.

The types of steel usually hardened in this manner are low carbon steels and low carbon alloys, with carbon content within the range 0.10% to 0.30%.

Heat Treatment

Heat treatment is used to actually alter the basic properties of an alloy or metal. The structure of a metal or alloy can be altered by heating it to specific temperatures and then cooling it down at a pre-determined rate. This impacts on the micro constituents of the metal, affecting the grain size, their nature and how they are distributed.

Heat treating offers a range of benefits which can be applied depending upon the final purpose of the metal in question. These include:

  • Removing strains created by cold working
  • Removing the kind of internal stresses created by processes such as welding, bending and drawing
  • Making the metal or alloy in question harder
  • Making materials easier to machine
  • Improving the capability of cutting tools
  • Making the material more resistant to wear
  • Changing the properties of a material to make it more resistant to factors such as heat and corrosion

Nitriding

Nitriding is a thermochemical heat treatment which takes place at a low temperature in order to improve the surface properties of components which have either been finished or are almost finished.

Nitrding takes place in mediums such as gas in the temperature range 490-560°C, or plasma heated temperatures of between 400 and 490°C.  It takes up to 90 hours, during which time nitrogen bonds with the surface of the material to create hard alloy nitrides up to a specific depth. Unlike other methods, such as carburising, nitriding doesn’t call for the material to be quenched afterwards.

Once it has taken place, nitriding offers extremely high levels of hardness, and is particularly useful for components which have to carry the weight of heavy loads, as it helps to protect against wear and increases the fatigue strength of the metal involved. Resistance to corrosion is also enhanced slightly and the fact that no high temperatures are involved means that any distortion to the metal in question is kept to an absolute minimum. Nitriding is often used for components such as camshafts, cam followers, gears, crank shafts, die casting tools and forging dies.

Metals that can be treated using nitriding

Nitriding works best when used on steels which contain elements which form nitride, such as vanadium, aluminium, molybdenum and chromium.

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