What are sprue cutters made of?
The handles and jaws of sprue cutters are made of steel, which is an alloy of iron and carbon. Many different types of steel used to make sprue cutters, including stainless, carbon, tool and chrome vanadium. The handle sleeves of a sprue cutter are made of plastic.
What is an alloy?
An alloy is a metal that has been made by combining two or more metals to produce a final product which has better properties than the pure elements from which it is made. Bronze is an example of an alloy.
Steel can also be alloyed with other elements (often referred to as alloy steel). This is made using more than 50% steel in combination with other elements, although the steel content of alloy steel is normally between 90 and 99%.
Stainless steel is a steel alloy which contains at least 10.5% chromium. The chromium helps prevent the steel from rusting by forming a protective layer of chromium oxide when exposed to moisture and oxygen. This protective layer prevents a build up of rust forming on the steel.
Carbon steel is available in three forms: low carbon steel contains less than 0.2% carbon, medium carbon steel contains between 0.2% and 0.5% carbon, and high carbon steel has more than 0.5% carbon.
Of these, only high carbon steel is suitable for use in making sprue cutters. This is because, unlike low and medium carbon steel, high carbon steel can be heat treated to further harden the material. This is important as a material is only capable of cutting another material that is softer than itself.
Tool steels are alloyed steels that possess high strength, hardness, wear resistance and toughness under impact, making them ideal for use in many tool applications. There are many different alloying elements that are used in the production of tool steels, some of the more common ones are: tungsten, molybdenum, vanadium, nickel, manganese, chromium and carbon.
By varying the ratio and quantities of these alloying elements it is possible to alter the final properties of the tool steel, making it suitable for use in different tool applications.
Chrome vanadium is a type of spring steel that was pioneered by Henry Ford for use in the Model T in 1908. It is an alloy of steel that contains approximately 0.8% chromium and 0.1-0.2% vanadium, which improves the strength and toughness of the material when it is heat treated.
Chrome vanadium is a very hard metal that has excellent resistance to wear and fatigue. It is now most often seen in tools sold in the European market.
What is the best type of steel for a sprue cutter?
While stainless steel offers the best corrosion resistance, unless you are going to be working or storing your sprue cutter in an environment with a high moisture content it is probably not the best choice as it will require more frequent sharpening than other grades of steel.
Whilst high carbon and tool steel will produce strong cutters that will keep their shape during normal use, chrome vanadium can be hardened to a greater extent. This means the jaws are less likely to develop nicks or burrs, so will require less maintenance.
Spring steel is used to make the springs that separate the handles or jaws of sprue cutters. It is a carbon steel with a very high yield point. This high yield point means it can undergo significant deformation before its shape is permanently affected. The ability to return to its original shape makes spring steel ideal for use in springs as well as many other applications.
PVC is the common abbreviation for polyvinyl chloride, which is a plastic polymer. PVC handles for sprue cutters and other tools are produced using a manufacturing method called dip moulding. PVC handles can be made in a wide range of colours, and are flame retardant and UV (ultra violet) resistant.
TPR (thermoplastic rubber) is a type of thermoplastic which combines the advantages of rubber materials with those of plastic materials.
Some sprue cutters will have handles that are made of two types of plastic: one will be a thermoplastic such as nylon and the second a TPR. These are sometimes referred to as being bi-material. The nylon is harder and used to give the basic shape of the handle while the the TPR provides more grip and a softer cushioned feel.