A versatile new range of milling cutters and inserts form an important part of Dormer Pramet’s first product launch of 2017.

Expanding the company’s comprehensive range of milling cutters, the new addition adds an adaptable option to support a wide range of insert shapes and operations from roughing to finishing.

The new SOD05 cutter, developed under the Pramet brand, reduces tool change-over time and inventory costs with its universal pocket capable of carrying octagonal, round and square inserts.

It means that the user-friendly cutter, available in a wide range of diameters from 32 – 125mm, can perform face milling, shoulder milling, slotting, plunging and ramping in steel, stainless steel, cast iron and non-ferrous materials.

To support the new cutter, Dormer Pramet has added to its range of octagonal (OD), round (RD) and square (SD) inserts. The OD insert has eight cutting edges and low cutting forces, promoting an economical option for face milling, while the RD inserts are suitable for high feed roughing, shallow profiling and ramping.

Its SD inserts have four cutting edges and offers a 90° option for square shoulder milling, providing high depths of cut up to 10mm. All types of inserts have the same radial and axial positions of edges – allowing for easier CNC programming and manual operations.

Meanwhile, Dormer Pramet has announced a new range of small diameter cutters (12 – 40mm) to offer further economical milling options. The cutters, which have a high number of teeth to improve productivity, are ideally suited for turn-milling.

To support this new cutter, a range of economical SOMT 05 inserts have been developed. With four cutting edges for general machining, the single sided inserts offer depth of cut up to 4.5mm.

The inserts feature a sharp geometry with narrow positive T-land and support shoulder milling, face milling, shallow slot milling and plunging in steel, stainless steel and cast iron.

Pramet has launched a new milling grade and also expanded its face milling range for stainless steels.

The M6330 grade has been developed specifically to achieve longer cutting edge durability and reliability in a range of difficult-to-machine materials with and without coolant.

Particularly suited to adverse cutting conditions, including interrupted cutting, the grade is now available with many of Pramet’s most popular inserts, including the ADMX, HNGX, LNGX, LNMU, OEHT and numerous other ranges.

It promotes greater operational reliability and tool life, with a high resistance to heat-related cracks. This is due to improved abrasion resistance from a new substrate and PVD coating.

The new grade is the latest of many new products recently launched by Pramet for machining stainless steels. Meanwhile, Pramet has also added to its face milling range for stainless steel with new, larger diameter cutters and inserts for greater depths of cut and more powerful machines.

These latest tools include the octagonal OEHT 09 inserts, suitable for unstable conditions and machining fragile components in stainless steels and soft steels up to depths of 5mm.

The versatile tool can be used for both roughing and finishing operations, providing increased tooling economy and significant savings on machine time.

In a recent product test, machining a piece of steel (3900mm x 3200mm) with coolant, the OEHT performed the roughing and finishing operation in 52 minutes. A competitor tool performed the same task in the same conditions in 252 minutes with roughing and finishing operations done separately.

A new range of round inserts, REHT 24, for face and copy milling and the XEHT 09 wiper inserts add to the options available. All can be clamped into the same milling cutter, further increasing versatility and cost efficiency.

A wide assortment of new milling cutters, ranging from 80 – 315mm diameter, is also available. Internal coolant delivery is supported by each cutter, including for large diameters.

An overview of all the new products launched by Dormer Pramet in April is available in its latest 2016.1 brochure. To order a printed copy or for more information contact your local Dormer Pramet sales office.

Dormer has added several new material specific carbide rotary burrs to its existing assortment.

The ST cut geometry is suitable for machining steels, while the VA design is for machining stainless steels. Available in a variety of shapes, both offer improved operator control and generate less temperature which, in turn, increases tool life.

These latest designs offer improved performance and up to 50 per cent higher metal removal rates, compared to standard carbide burrs.

In addition, the new GRP cut is for machining fibreglass and composite materials. Available with drill point and end mill styles, its design reduces splintering and improves entry and exit surface quality.

To support the introduction, Dormer has added three new sets to its burrs assortment. This includes five piece sets featuring the ST cut for steels, the VA design for stainless steel and a coated Double Cut set.

Dormer launched its new range of carbide burrs 12 months ago to enhance its ancillary tools program for general machining applications. The comprehensive assortment of designs and shapes include ball nosed cylinder, pointed tree, oval, flame, 60° and 90° countersinks, cones and inverted cones varieties.

Meanwhile, a new high speed cobalt (HSS-E) jobber drill has been launched by Dormer. The A147 is primarily for machining stainless steel and titanium.

Capable of drilling to depths up to 6xD, the Bright finish A147 features a split point geometry. This improves penetration through the work-piece allowing for reduced torque requirements, improved hole-quality and longer tool life.

Its addition supports Dormer’s existing high speed steel (HSS) quick spiral jobber drill – the A108 – which also machines stainless steel in general applications.

Dormer’s versatile A147 can also be used for a wide variety of materials including steel, copper and aluminium.

Pramet’s range of turning tools for stainless steel has been further extended with the launch of a new chip breaker and wiper inserts.

The NMR chip breaker provides a reliable option for longitudinal and face turning with high stock removal in medium and roughing operations.

This new geometry further enhances Pramet’s range of double-sided chip breakers for all turning stainless steel applications, which already includes NM for medium turning and NF for finishing to medium turning.

NMR’s positive geometry offers increased reliability through its strong cutting edge, which features a protective peripheral land. It is ideal for heavy machining and less stable conditions, with higher metal removal rates and predictable insert behavior providing increased tool life and productivity.

The NMR chip breaker is available for many types of Pramet inserts, including CNMG, DNMG, SNMG and TNMG.

Meanwhile, Pramet has also launched a new range of wiper inserts for turning.

Compared with standard inserts, the W-FM and W-NM wipers promote increased productivity by supporting higher feeds, as well as high quality machined surface, due to its new wiper edge.

In straight turning and facing operations, the smoothing effect of the wiper results in improved quality of surface roughness. If used properly, it can prevent the need for additional grinding operations, saving further costs.

Single-sided positive inserts with the W-FM positive geometry are suited to machining stainless steel and steels. The double-sided negative inserts with the W-NM highly positive geometry are ideal for machining stainless steel and low carbon steels.

Both feature a positive front land which further promotes smooth machining.

Stainless steel is a vitally important material for many industries around the world. Even though it was created more than 100 years ago, use of the material has increased significantly since the turn of the 21^st century.

Ricky Payling, application specialist at Dormer Pramet, outlines the growth of stainless steel, how the cutting tool industry has evolved to machine the material, as well as providing a summary of some of its most common grades.

According to the International Stainless Steel Forum (ISSF) the global demand for stainless steel products has nearly doubled in the last 20 years, and continues to grow five per cent each year.

In 2014, almost 42 million metric tons of stainless steel was produced worldwide – a 70 per cent increase from 2005 (24 million metric tons). This growth is predominantly achieved by an increase in China, where production has grown from a 13 per cent share of global output in 2005 to more than 52 per cent in 2014.

This rapid development is not only to meet worldwide demand, but also to support increased use within China, where stainless steel is consumed in household metal products, building materials and machinery.

Stainless steels’ anti-corrosive qualities make it perfect for use in a huge range of environments and components, such as aerospace, general engineering, consumer, oil and gas, medical and marine industries.

Its versatility is reflected by the fact that there are more than 150 different grades. Common stainless steels include ferritic, martensitic, austenitic, super-austenitic and duplex. More details of which are covered below.

The main alloying element is Chromium, which forms an ultra-thin oxide film on the surface. As a general rule, resistance to corrosion and oxidation increases in line with Chromium content. Other alloying elements, such as Nickel and Molybdenum, can be added to change the structure, increase corrosion resistance and improve strength.

This increase in production and consumption has coincided with advancements and new developments within the cutting tool industry. Due to the difficult process of machining stainless steel, manufacturers have invested a huge amount of time and resources in finding new ways to try to combat the numerous application challenges.

Recent introductions include changes to the cutting tool design, new geometries, improved coolant and developing stronger coatings to improve performance and tool life.

Drills with thin margins for example, reduces the contact with the hole surface, minimising friction between the cylindrical land and the hole walls, decreasing work hardening and temperatures generated.

Positive point geometries ensure excellent chip breaking and evacuation, while a specially designed web combines the benefits of maximum rigidity with space for efficient chip removal, reducing machine downtime.

Coatings and coolant
Significant heat is generated during machining of stainless steel, resulting in plastic deformation and severe crater wear. Therefore, a generous flow of cutting fluid removes heat from the cutting edge, helps chip breaking and improves dimensional stability of the component.

When using flood coolant, it is important to ensure a plentiful supply as any period of coolant starvation can cause temperature fluctuations. This can cause thermal cracking, resulting in reduced tool life. Cutting tools with through coolant also provide an instant reduction in temperature and supports chip evacuation.

Meanwhile, a Titanium Aluminium Nitride (TiAlN) coating is ideally suited for machining stainless steel as it holds its hardness at higher temperatures due to a layer of aluminium oxide, helping to transfer the heat away from the cutting tool.

The high strength of stainless steels combined with their high ductility makes chip breaking more difficult. This increases the risk of vibration, which can affect surface finish quality and reduce the service life of the tool or insert.

To address this, always make sure tooling and work pieces are stable and well clamped. Always keep tool overhang to a minimum, especially when drilling or internal turning. To help reduce vibration, use sharp tools or inserts with a small nose or corner radius.

Ferritic & Martensitic
The machinability of ferritic and martensitic stainless steels shows a resemblance to that of ISO P: Steel. Normal chromium content is 12-18 per cent, with only small additions of other alloying elements.

Ferritic materials are used in shafts for pumps, steam and water turbines, nuts, bolts, hot water heaters, and in the pulp and food processing industries. Martensitic steels can be hardened and are, as a result, used for edges in cutlery steel, razor blades and surgical instruments.

Machinability of ferritic and matensitic stainless steels is good and very similar to low alloyed steels.

Austenitic & Super-Austenitic
Austenitic stainless steels are the most commonly used ISO M material, accounting for 70 per cent of all stainless steel machined. This is due primarily to their very good resistance to corrosion.

The most common composition is 18 per cent chromium and 8 per cent nickel. Steel with greater corrosion resistance is created by adding two to three per cent molybdenum, often called “acid-proof steel” or type 316.  Super-austenitic stainless steels have a nickel content of more than 20 per cent.

Austenitic and super-austenitic stainless steels are used where good resistance against corrosion is required. Typical industry sectors include the chemical, pulp and food processing industries. It is also used in aircraft exhaust manifolds.

Austenite stainless steel produces tough, long, continuous chips that are difficult to break. It is prone to work hardening during machining, producing hard surfaces and chips which lead to notch wear. It also creates adhesion and produces built-up edge, resulting in poor surface finish and reducing tool life.

To minimize this, avoid using tools with worn edges which could accelerate tool wear and cause breakage. Make regular checks for signs of wear and change tools or inserts regularly. Also, try to avoid any dwells or pauses in the cutting process as this will cause heat build-up and increase work hardening.

A high rake angle reduces heat generated during milling, minimising work hardening.

Duplex
Adding nickel to a ferritic chromium based steel will form a mixed base structure containing both ferrite and austenite. This is known as a duplex stainless steel.

Duplex materials have a high tensile strength and maintain very high corrosion resistance.  Super-duplex and hyper-duplex indicate higher content of alloying elements and even higher corrosion resistance.

Chromium content between 18-24 per cent and nickel content between 4-7 per cent are common in duplex steels, producing a ferritic share of 25-80 per cent.

Duplex stainless steels are used in the chemical, food, construction, medical, cellulose and paper making industries, and in processes that include acids or chlorine. They are often used in equipment related to off-shore oil and gas applications.

Machinability of Duplex is generally poor due to high yield point and high tensile strength. Higher content of ferrite – above 60 per cent – improves machinability.

Dormer Pramet has developed a comprehensive assortment of indexable and rotary cutting tools to support machining of stainless steel.

Its solid carbide drill for applications up to 8xD has been specifically developed to overcome problems typically associated with deep-hole drilling of stainless steel. Created within the Dormer product portfolio, the R459 broadens the existing MP-X range which already consists of 3xD and 5xD solid carbide multi-material drills.

Meanwhile, a versatile range of OEHT octagonal inserts for cutting depths 4 – 10 mm, alongside REHT (round) and XEHT (wiper) inserts, is suitable for stainless steel.

By utilising eight cutting edges – the highest number available for positive inserts – the new range provides an economical offer for customers, while the wiper insert option boosts feed rate capabilities and surface finish quality.

Courtesy: Dormer Pramet
 

Dormer Pramet has added a range of carbide rotary burrs to enhance its support tools program for general machining processes.

It is the first time that burrs will be available under the Dormer product brand, with a comprehensive assortment of designs and shapes to choose from, including ball nosed cylinder, pointed tree, oval, flame, 60° and 90° countersinks, cones and inverted cones varieties.

The introduction of the burrs is part of a wider product launch by Dormer Pramet on 1 April 2015 – the first combined unveiling since Dormer and Pramet merged last year.

Dormer’s wide selection of burrs provides numerous options to machine a range of materials, including hardened steel, non-ferrous materials and plastics.

Its combination of carbide head and steel shank (above 6mm) provides an ideal mix of rigidity and strength. This feature reduces vibrations, resulting in a consistent and secure performance, as well as an improved tool life. A double cut design on Dormer’s burrs improves ease of control, increases metal removal rate and breaks swarf into manageable pieces.

Also, the ball end geometry incorporates skip flute grinding which improves cutting action closer to the centre, reducing the chance of swarf congestion and increases strength.

Alternatively, the aluminium cut option makes it the first choice for non-ferrous materials and plastics. The high helix and rake angle offers large flute volume for rapid material removal rates. Dormer’s burrs are available with TiAlN coating to increase tool life in difficult conditions and help to resist ‘built-up edge,’ which is common for cutting tools with small flute volumes.

Note: The merger of round tools manufacturer Dormer Tools and cemented carbide tooling specialist Pramet Tools was instigated in 2014. The combined product programme now encompasses a comprehensive range of rotary and indexable drilling, milling, threading and turning tools for the general engineering sector. An expanded sales and technical support service extends to over 30 offices serving more than 100 markets worldwide. These are supported by state-of-the-art production facilities in Europe and South America and a global distribution network consisting of five strategically placed hubs.