What is stainless steel?
Stainless steel is a metal with high chromium content. Chromium does not oxidise or rust.
What types of stainless steel are available?
Stainless steels come in a vast variety of metallurgical make ups and finishes but the most common ones are 316, 303 and 304. These numbers denote how much chrome, nickel and iron is in the steel.
What are the common grades of stainless steel used for?
316 stainless steel is used for surgical instruments and anything used in the food processing industries.
303 grade has less chrome thus is less expensive; this is normally used as a free cutting material for high speed turned parts on lathes i.e. kitchen cupboard handles.
304 stainless steel is freely available in sheet form and is used in the flour milling industry as well as other not so critically hygienic facilities. It’s also commonly used for nuts and bolts for motorcycles. I prefer 316 stainless for nuts and bolts because it has a higher tensile strength.
What Stotfold engineering makes with stainless steel.
We can make anything in any grade of stainless steel but we refuse to use inferior grades for our customers needs.
The reason being, we like our products to look as new in a hundred years time as though they had just been made. We use stainless steel 316 grade for almost everything unless specified otherwise by the customer.
Stainless steel petrol tanks, oil tanks and all sorts of custom parts are made in 316 stainless steel. 316 stainless nuts and bolts are superior to the 303 grade that almost all custom nut and bolt suppliers sell.
The advantages of using 316 stainless
When an exhaust pipe manufacture mass produces a pipe for, lets say a motorcycle it is generally made of mild steel tube and bent in a mandrel to give it the desired shape. Manufactures always, of course look at the profit margin and ease of manufacturing. After the pipe has had its brackets and fittings welded on it goes to the chrome plating shop to be plated.
The chrome plating process uses electricity, poisonous chemicals and a lot of hazardous waste products, not a very green business to be in. Particularly when the exhaust pipe has to be restored in years to come and go through the whole process again.
Stainless steel 316 bypasses all of these plating processes, it only has to be polished to a mirror finish and the job is complete, and when in years to come the pipe has lost its lustre without rusting and rotting, it just needs a re-polish, the pipe will last for generations and when it is time to sell your machine, there would be very little restoration to be done if all the nuts, bolts, brackets and such like were all made from 316 stainless steel.
Prices of stainless steel
The costs involved in manufacturing a product in stainless steel are marginally higher initially; this is due to it being tougher than mild steel making it harder to cut on a machine and a little more difficult to form into pressed parts such as brackets. But in the long run stainless 316 pays for itself. If we were to look at a balance sheet on the cost of stainless 316 as apposed to mild steel we will see where stainless comes to the fore.
Stainless steel 316, tube length of 1 metre is £20.00. The tools to work stainless steel are around £20.00. The welding is £5.00 and the finish polishing is £20.00
Mild Steel tube of the same length is £4.00, the tools are £6.00, the welding is £5.00 and the polishing and plating is £40.00.
After 25years the stainless pipe requires approximately £40.00 polishing but the mild steel pipe requires stripping the chrome nickel and copper and then polishing, sometimes to wafer thin thickness to remove all the rust pock marks and then re-plating, the cost if there is no brazing or welding repairs to be carried out is £100.00
The cost of stainless £105.00
The cost of mild steel £155.00
It is obvious that stainless steel 316 is not used on something as simple as an exhaust pipe because mid to long term failure bring repeat orders to the mass producer who is unconcerned with green issues