Information Library

Material Grades and Uses: Material Specification and Machining Guide

EN1A, EN1A(PB), 230M07

Mild Steel that is very easy to machine to a good surface finish, it contains a percentage of lead or substitute which makes it unsuitable for welding. It is most commonly used in mass produced (CNC) items because of the ease of which it can be machined which aids to extend tool life. This material is also available as EN1APB which is a 'free cutting' derivative. Poor corrosion resistance.

Common uses: Low stress fittings including hubs, casings, handles, linkages and decorative items.

Not Suitable For: Stressed items subjected to tensile loading such as bolts, studs or high wear applications as the surface will tend to dull and 'pick up' onto mating materials. Material rusts very readily if left unprotected. Although this steel can be welded, it is not recommended as the parent material will tend to 'rip' about the welds when stressed. Moderate to high shear loading will cause failure.

Machining: Very easy material to machine, especially the 'PB' derivative with basic tooling.

Finishing: To achieve the best finish and accuracy, EN1A should be machined at high surface speeds and feeds with a general purpose carbide tool, though HSS can be used to good effect. Screwcutting is very easy with little tearing and obtaining an exact machined size with a good finish is easy to repeat.

Can be machined dry but most lubricants are suitable and recommended, beware that some cutting oils may cause surface staining.

EN3, EN3B, 070M20

Mild Steel that is fairly easy to machine but has a tendency to rip if unlubricated. It is very easy to weld and is suitable as a general purpose machining/fabricating steel. EN3 is mild steel as a round profile, EN32 is mild steel as a rectangle profile, they are both essentially the same material.

Common uses: Lowly stressed fixings, shafts, spacers, hubs, bushings, linkages, frames and supporting fabrications. Fair corrosion resistance.

Not Suitable For: Highly stressed components, especially under high tensile shock loading where the material will likely yield and distort, bend or fracture.

Machining: Fairly easy material to machine but does stress relieve readily. Long round shafts can tend to bend slightly during rough machining and long flats will bend upwards towards the cutter as the surface is machined away. Certain components should be machined smaller than stock sizes to avoid this problem so as to allow roughing cuts before finishing. The material is prone to minor rutting during machining so speeds and feeds need to be selected carefully to achieve best results.

Finishing: For best finish and accuracy, EN3/EN32 must be machined with coolant or lubricant. Soluble fluid ('White water') is suitable for most applications, but fine machining will benefit from the use of a cutting fluid to be used during final finishing. Rutting can be a problem so it can pay to allow material for final finishing via emery (P80, 0.001"-0.002") or honing.

EN8, EN8D, EN8M, 080M40, 080A42, 212A42

Medium strength steel that is suitable where good all round performance is required. Better mechanical properties than mild steel (EN3) and can be through hardened. Available as general machining steel (EN8 080M40), with increased wear resistant properties (EN8D 080A42) and also as a free cutting alternative (EN8M 212A42).

Common uses: Hydraulic rams (chrome plated), key steel, medium torque shafting, tensile fixings and gears. Good for shock loading and where cold bending with reduced breakage or cracking is desired. Good case hardenability. Fair corrosion resistance.

Not Suitable For: Highly stressed components, especially under high tensile shock loading where the material will likely yield and distort, bend or fracture.

Machining: Material has a tendency to rip when machined which will leave rutting and score marks. Screwcutting can tear on fine threads. Best machined using carbide inserts at a medium to high speed but care must be taken on the feedrate to obtain best surface results. Material tends to respond better to deeper machining cuts over fine cuts. Final polishing is likely so allow 0.002"-0.003" on final dimensioning. 'DM' version machines far easier but at the cost of reduced corrosion resistance.

Finishing: For best finish and accuracy, EN8 grades should be machined with coolant or lubricant. Soluble fluid is recommended, but fine machining will benefit from the use of a cutting fluid over the final cuts. Rutting can be a big problem so pay particular attention to correct speeds and feeds and expect to allow material for polishing, grinding or honing.

EN16, 605M36

Medium to high strength steel that shares many of the good mechanical properties of EN8 but is far more resistant to shear loading and frictional wearing. Commonly pre-heat treated to condition 'R' or 'S', which maintains machinability but with the benefit of increased mechanical properties.

Common uses: Tolerant shear pins, connecting rods, crossheads, pistons, high load couplings and hubs. Resists shearing and bending but with the added ability to 'give' before terminal breakage.

Not Suitable For: EN16 is a very good all round performer, with the exception of material cost to hold against it. Components that require a highly polished surface (such as sliding or rotating seal diameters) may suffer as a result as to the dull surface that EN16 can offer.

Machining: The material is very similar to machine as EN8, showing a reluctance to polish to a bright finish and has a very slight golden colour to the surface which develops over time. Screwcutting is fairly easy with less ripping than EN8 but copious quantities of high pressure cutting fluid is recommended.

Finishing: For best finish and accuracy, EN16 should be machined with coolant or lubricant. Soluble fluid is recommended, but fine machining will benefit from the use of copious amounts of cutting fluid over the final cuts. Rutting can be a big problem so pay particular attention to correct speeds and feeds and expect to allow material for polishing, grinding or honing. Cutting fluids will have a tendency to stain the surface so ensure that all traces are removed for final finishing.

EN19, 709M40

High strength steel to be used when a very high tolerance to shock loading is required, suitable for uses in areas of very high loading such as gear box components etc. Material has slight corrosion resistant properties and is possible to machine very accurately to a fine surface finish. Can be vacuum induction hardened leaving a fine finish.

Common uses: Tow pins, high load studding, gears, shafts, racks, pawls and load bearing tie rods.

Not Suitable For: Suitable for most applications where strength is the main requirement, but higher material cost and machinability should be considered.

Machining: Quite a tough material to machine, turnings can be long and wiry and obtaining chip breaking can sometimes be a problem, especially with HSS turning tools. It is easy to machine to fine dimensional tolerances using indexable carbide cutting tools. Generally we find that using a stainless grade of carbide provides better results.

Finishing: It is fairly easy to obtain a fine surface finish as long as tool selection, speeds and feeds are set correctly. Only basic polishing will be required so final dimensioning is possible without leaving extra material. HSS tools can be used but the old fashioned method of radius tooling provides good results, at a cost of machining speed.

EN24T, 817M40

High strength steel that is easy to open flame heat treat and temper. High quality material for stressed components and usually supplied in 'T' heat treated condition. Maintains machinability but with the added characteristics of heat treated steel.

Common uses: Used for the production of punches and dies because of its easy hardenability, drill bushings, bearings surfaces, high strength shafts, gears, hubs, screws and fixings.

Not Suitable For: Shock loading is limited because the likelihood of failure is increased with the added hardness. Cracking and distortion can occur during heat treatment so sharp edges should be rounded where possible and drilled holes should be positioned away from sharp changes of profile. Surface scaling and material growth may occur during the heat treating process.

Machining: Tough to machine but still possible with HSS. The use of carbide is recommended, chip breaking is easily achieved with moderate tool feeds and correct speeds. Easy to produce a high quality surface finish to high tolerances and higher surface speeds can be used on final cuts (with the correct tooling). Best roughed out at a slower speed and higher feed rate with plenty of coolant. Finishing cuts are better with moderately high surface speed and aggressive feed. Material can be machined when hardened with stainless grade tips or ceramics.

Finishing: Using carbide is recommended to obtain best surface finish results. HSS can be used but best kept for forming rather than running surfaces. Polishing can be kept to a minimum as the surface finish will generally be good as long as coolants and high pressure lubricants are continually used during final cuts.

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