But all aluminiums are not equal! It’s vitally important to select the grade that is most appropriate for your component to meet form, fit, and function requirements as well as supply, cost, and machining factors.

The 200 series of stainless steel is an austenitic alloy containing low amounts of nickel. It is non-magnetic and has low corrosion resistance. It is mainly used for general purpose metalwork.

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The V7 Inox is another excellent range for machining stainless steel. The special TiALN coating helps offer excellent wear and heat resistance when machining tricky materials such as 303, 304 and 316 stainless grades. The V7 inox also has a variable helix for vibration free milling with excellent tool life.

At the lower end of the budget, some General Purpose Milling Cutters are suitable for milling Stainless Steel. These include our K2 Carbide range from YG-1 or the low cost Mammut Milling Cutters, both of which are available in a wide range of geometries for a range of applications.

Aluminium 6082 is the highest strength in the 6000 series and overall, a medium-strength commercial alloy. In plate form, it has become the most widely CNC machined aluminium alloy due to its low cost and good machinability, with high efficiency being easily obtainable.

“6082 is easy to source and quick delivery is achievable on most sizes. It’s also the cheapest grade of machinable aluminium. Us CNC machinists like it because it machines well, meaning less cutter wear and faster speeds and feeds, resulting in reduced cycle times. So unless your application needs the superior properties of other grades of aluminium, 6082 is a good bet.”

In Aerospace the ability of stainless steel to withstand extreme temperatures and it’s resistance to rust means it is used in the frames and engines of an aeroplane. The strength and rigidity of stainless steel also makes it ideal for handling a planes weight, therefore the aviation industry use it to produce landing gear.

6082 is used across all market sectors because it’s readily available, machines well and a range of surface treatments can be applied. Applications include but are certainly not limited to highly stressed applications, structural applications, and packaging. The aerospace equivalent “L Grades are commonly used in military, defence, and aerospace applications.

Aluminium 7075 is known for its exceptional strength comparable to many steels. As a result, it’s a popular choice for highly stressed structural parts and safety-critical components such as rock-climbing equipment, bicycle components, and regulating valve parts.

“2014A has high strength but poor corrosion resistance. Parts are often anodised in order to protect the surface of the metal. It’s great for parts needing good strength up to 150°C. Should the extra strength not be critical, aluminium 6082 which has excellent corrosion resistance, may be a better and cheaper option.”

Milling304stainless steel

Korloy also offer Stainless Steel turning options for heavy turning (large depths of cut), sliding head lathes and fine finishing.

There is no one-size-fits-all when it comes to selecting an aluminium grade for your CNC machined component. For an ‘all-rounder’ material with good properties, low cost, and ease of availability, I recommend aluminium 6082.

One crucial thing to consider when machining stainless steel is to watch out for rubbing brought on by tool chatter (machine vibration). This is due to the exceptionally hard characteristics of the material, therefore it is important that the machine and tooling used are correct for the application.

Cutting speed forstainless Steelwith carbide

Korloy’s Range of Turning Inserts feature a huge range of application specific turning inserts for stainless steel; the dedicated Inox range includes:

Selecting the appropriate material and grade is among the important early decisions you’ll make when designing your CNC machined component that will have a knock-on effect on your supply chain, the commercial viability of your component, and whether it’s fit for purpose.

Modern Stainless-steel cutters, now have special geometries such as corner edge preparation and multiple/variable helix with uneven flute spacings. These features can lead to much better tool life and can improve performance greatly.

Despite stainless steel being used in demanding environments, the intricacies of the medical industry also benefit from its characteristics. Surgical and dental instruments as well as implants (replacement joints and artificial hips) are all made from stainless steel. It can also be used to build operation tables, MRI scanners and plates to repair broken bones.

Aluminium is a versatile metal and a popular choice for CNC machined components, known especially for its high strength-to-weight ratio.

There are many crossovers between an exotic material and stainless steel due to the fact that the base material of exotics can in fact be Stainless Steel itself, such as Super Duplex.

When choosing between a HSS or a Carbide tool for stainless steel there are a few things to consider. Machine capability is one thing and if you are limited on speeds and feeds then a HSS tool should be used. However, if your machine can run at higher speeds and feeds then carbide would be advised. If your carbide tools are prone to chipping then a powder metal substrate would be suitable due to them having the toughness of HSS but running at higher cutting data.

The cooling characteristics of a cutting fluid are most important when machining stainless steel however coolant does also reduce tool wear and help keep the swarf away from the job.

In the automotive industry Stainless Steel has been used since the 1930’s for producing exhaust systems, grills and trims. Modern technologies now also allow manufacturers to also produce structural automotive components too.

Our Experienced Technical Engineer Tom answers all common questions about Stainless Steel including machining tips and the best drills, cutters and taps for machining Stainless Steel.

Stainless SteelSFM chart

Titanox milling cutters are the go to range for Stainless Steel based exotic materials as well as Stainless Steel itself and Titanium. It features a unique double core geometry. This helps with chip flow and protects the flutes from clogging when machining. A range which hugely improves end milling and slotting operations. Similar to the V7 Plus, Titanox also includes the heat resistant Y1200 coating which offers high feed rates, large depths of cut and excellent tool life.

4.    Duplex – This is an alloy that is half austenitic and half ferritic. This alloy is also magnetic and provides superior strength and corrosion resistance.

The chromium properties make Stainless Steel more resistant than Steel to rusting, staining or corrosion. It is also typically non-magnetic.

The Jetpower range is a high performance option, suitable for when you have a lightweight machine or have power limitations. It is made from ultra-fine micrograin carbide making it super wear resistant. If you have a manual machine, this provides great performance when you have vibration. It creates very low cutting forces, providing excellent surface finish and chip control.

2014A aluminium is a readily available high-strength grade of commercial aluminium. It is commonly used for high-strength structural components and high-technology market applications. Supplied in a fully heat-treated condition, 2014A is a 4-5% copper alloy.

Tool selection is essential. Steel itself can be difficult, therefore Stainless Steel requires even more thought and planning in selecting the proper tool to avoid any issues. Due to the potential issues surrounding vibration (chatter), a variable helix tool should always be considered. The special design can create something called ‘silent machining’ thus improving surface finish.

Aluminium is a lightweight material, meaning the strength behind stainless steel makes it much heavier. Around 2 thirds heavier in fact.

Cutting fluids should be used when machining stainless steel. The reason for this is that it can lead to overheating, which in some cases can reduce the required corrosion resistance of the material. Work hardening can also be an issue where the heat generated from friction can cause the material to harden, thus making it more difficult to machine.

“5083 has good ductility for the strength level. Take note that the material size range and availability is far more restricted than 6082, so is recommended only where the properties are required.”

YG-1 Turning Inserts offer a lower cost range but are still considered a performance option with material specific grades. The YG213 grade is a for medium to high speed continuous & light intermittent turning. The YG214 grade is tougher for low speed rough and heavy intermittent turning.

Coolant which has a high oil content is always good to use on stainless steel because of it being considered a sticky material (similar to aluminium).

Cutwel have the UK’s largest range of Milling Cutters, with ranges available for every application, material, size & performance.

Here at Penta, we have a wealth of experience in machining aluminium, and we certainly have our favourites. In this blog, I’ll outline the four aluminium alloys we recommend most often, covering most applications (with a bonus one at the end).

304stainless steelcutting speed

The reality is that selecting a material is amongst the most important decisions you’ll make about your component design and it’s not something you want to rush or skim over.

If you need further guidance, I highly recommend seeking the expertise of a CNC machining company. Here at Penta, we offer a design-for-manufacture service that includes material recommendations as well as optimising your design for machining and cost efficiency.

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Some stainless steels, such as austentic, can form long spiral swarf which can cause a build up and be difficult to remove. To prevent the problem occurring in the first place, we would advise a tool with a chip breaker to keep the size of the swarf to a minimum.

I couldn’t write a blog about aluminium grades and not mention 6061. We get a lot of enquiries about 6061 but the truth is, it’s much more commonly used in America.

This leads us nicely on to the machine itself. A CNC machine is usually considered to be faster and more cost effective than a manual machine which is generally a requirement of optimal stainless steel machining. You should always machine stainless steel at the required surface feed and speeds, therefore researching the cutting data of the tooling you will be using is always advised before purchasing a machine; just so you aren’t limiting your capabilities. Machining using the correct data will ensure the best performance and tool life whilst reducing the risk of any damage or breakages.

The number one cutter I would recommend for machining stainless steel is the V7 Plus. This range provides extreme tool life and gives excellent performance when finishing or roughing. The V7 plus has an advanced YG1200 coating which means it can withstand temperatures of up to 1200 °. It has a multiple helix geometry which allows for larger depths of cut and higher feed rates. As well as this, the V7 Plus also features a variable helix and unequal flute spacing. The benefit of this is zero vibration for an exceptional surface finish. There are also 2 advanced geometries of V7 plus; the TRP range for trochoidal milling and the Chip splitter which creates shorter chips (ideal for longer chipping swarf from austenitic stainless steel) to enable double the length of cut as the standard V7 plus range.

Whether roughing, finishing or a bit of both, Cutwel provide a range of dedicated high performance grades and chipbreakers for stainless steel turning applications. We supply the UK’s largest range of Carbide Turning inserts and CBN Turning Inserts from global leading manufacturers Korloy and YG-1.

However, if you need a higher strength, you will want to closely look at 7075 or 2014A and if you need excellent corrosion resistance in salt water, 5083 could be just what you need.

The aerospace equivalents are L93 (plate), L157 (sheet) and L168 (bar) which are used to make aerospace fittings, military vehicles, aircraft structures, truck frames, and weapons.

2.    Martensitic - The least common type of alloy. This stainless steel has high carbon contents, which allow them to be tempered and hardened.

Speeds and feedsfor drilling 304stainless steel

Stainless steel is also generally harder, meaning it is less malleable with lower thermal conductivity and heat distribution.

Cast Iron is also more prone to corrosion and rust than Stainless Steel however it does have better anti-vibration properties which makes it less complex to machine.

When selecting the best tooling for stainless steel, it is important to also consider other aspects such as the tool holders that will be used. This can mean moving away from standard ER Collet Chucks and moving to other high-performance holders, such as a Hydraulic Chuck. By doing this, it can improve the surface finish and massively reduce cycle times.

Exotic materials tend to have a higher temperature resistance than Stainless Steel. The combination of a range of chemical properties involved in exotic materials also make them stronger, with better corrosion and acid resistance.

Stainless Steel speeds and feedscalculator

To get you started in your research, here at Penta, we have put together a comprehensive materials resources area of our website which breaks down all the common materials and grades we encounter regularly.

Stainless steel metal does not rust as easily as ordinary steel, nor does it stain or corrode. Most stainless steels are made from recycled steel, and once this happens its qualities do not deteriorate which means it can be continuously reused.

My advice is to steer clear of 6061 and instead opt for 6082 which has very similar properties but is much more readily available in the UK, with quicker lead times and significantly lower cost.

The 300 series of stainless steel is mainly austenitic, and these grades are quite versatile. 304, also known as A2 is the most commonly used austenitic stainless steel. It contains high amounts of chromium and nickel which give 304 stainless steel excellent corrosion resistance. It is also magnetic. Grade 316 has high amounts of nickel and chromium. A big difference is that 316 contains a significant amount of molybdenum.

The 400 series stainless steel has a high carbon content. This provides high wear resistance and strength. This series can be hardened by heat whereas 300 series grades cannot. They are also much stronger and more magnetic. Grade 410 is the most used of the 400 series.

Cutwel’s Inox tap range is specially designed for coping with the demands of stainless steel. Our Machine Taps for Stainless Steel (Inox) result in reduced friction, have low torque and offer the most reliable performance. With a variety of thread forms available, including Metric Coarse, Metric Fine, UNC (Unified National Coarse), UNF (Unified National Fine) and BSP(G) (British Standard Pipe). Optional through coolant taps are available with radial flow for through holes and axial flow for blind holes.

SFM forstainless steeldrilling

Stainless Steel is harder than aluminium providing extra strength. However, it has low conductivity and isn’t very malleable.

There are many factors to consider when machining stainless steel, particularly because this material is more challenging than standard steel and also materials with a higher alloy content are generally more difficult too.

Stainless Steel is also used in a wide range of other industries including the building trade, food and catering industry and in nuclear applications.

A sharp cutting edge should also be at the forefront when machining stainless steel because it increases accuracy and ensures a smoother cut into the material. Re-sharpening should be done as soon as possible after any slight sign of deterioration.

SFM forstainless steelturning

Stainless steel is considered to be a soft metal, which means that it’s not great for heavy duty applications. It can still be hard to machine due to its toughness and durability, therefore needs the right techniques and tools to machine efficiently.

There are different grades and surface finishes, depending on where stainless steel is used. Different stainless steels have certain amounts of metals in them, and they are suited for all types of purposes. Grades of stainless steel are generally categorised into different series:

There are dozens of grades of aluminium so it’s easy to see how it can get confusing and overwhelming when deciding which to choose for your application.

“We love aluminium 7075 for its superior strength compared to other aluminium alloys. But beware, this strength does come at a cost. If you don’t need that extra strength, opt for a lower-cost aluminium such as 6082.”

Stainless steel is an alloy (mixture of elements) mainly made from carbon and iron; It also contains chromium. For steel to be considered as stainless steel, it must contain at least 10.5% chromium.

1.    Austenitic - The most common type of stainless steel. These tend to be non-magnetic. They have a high amount of chromium content and harder to machine.

Besides the Inox tap range, Cutwel also offer YG-1’s Prime-X Coated Machine Taps which are also excellent for stainless steel tapping. Providing extremely high cutting speeds and increased tool life, these taps give high and reliable performance on a wide range of materials. With highly improved wear resistance and a patented special geometry which prevents tap failure due to overfeeding.

5083 is a medium-strength aluminium alloy and the highest strength of all non-treatable aluminium alloys. It’s particularly known for its exceptional performance in extreme environments, including its resistance to saltwater and chemicals, making it a popular choice in marine and petrochemical industries.

The aerospace equivalent, L95, is widely used in aerospace, nuclear and military applications. 7075 is not recommended for applications where corrosion resistance is needed.

In summary, when machining Stainless Steel, the key is to be quick. You can run the danger of work hardening your material if you take too long, which could result in early tool failure.