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L Krishnan, Managing Director, TaeguTec India

Viewpoint The changing scenario of tooling industry

Dec 22, 2016

In recent years, materials with unique metallurgical properties — such as titanium, tool steels, stainless steels, hardened steels and other superalloys — were developed to meet the demands of extreme applications. This, in turn, opens up new challenges in machining those materials. The toolmakers are constantly experimenting with different geometries and new insert grades so as to ensure better surface finishes, while lowering the machining costs. The view-point section discusses the changing scenario of the tooling industry.

“Sustainability drives the development of dry machining”

- L Krishnan,
Managing Director,
TaeguTec India

What are the latest developments in the tooling industry to meet the challenging requirements in machining difficult-to-machine materials?

Stable tool life is a critical aspect of a stable process for ensuring quality and productivity. Tooling technologies are continually being developed to meet and exceed expectations. Cuttingedge design based on the material and operation is a critical element of development. Appropriate cutting-edge geometry together with right edge condition is also important. Base grade of carbide and its hardness (wear resistance) and toughness (transfer rupture strength) is essential to ensure good tool performance. Maturity of tungsten carbide powder manufacturing and R&D efforts ensure this.

The right type of coating such as CVD/PVD is the next important consideration. Based on the operation, the material of component being machined, and tool failure pattern, the right coating is selected and evaluated. For tools requiring sharper cutting edge, PVD is preferred over CVD coating. Overall use of PVD as coating process is widely used and is gaining more acceptances. These factors together with expert application support help to meet customer demands.

What role does tooling play in the context of machining composite materials that requires
different mechanism of material removal?

Machining of CFRP remains a challenge for the industry due to its inherent material structure. The machining process should ensure that there is no de-layering after machining. A sharp cutting-edge with excellent wear resistance is ideal. Diamond coating is, thus, widely used together with special geometry and edge condition. The shape and size of the parts do pose challenges to work-holding and machine tool industry.

What are the trends in dry machining? What would be your recommendations to get the most
out of the tooling operation, while dry machining?

While dry machining is popular in machining cast iron and roughing of steel, wet machining continues to be the popular choice. Environmental concerns will increasingly drive the development of the dry machining process. One of the major challenges today is evacuation of heat generated during machining so that it does not impact components and this result in thermal changes in the machine, which may impact accuracies during finish machining processes. Technologies are maturing in this direction and a lot of work is being done to meet emerging demands.

“Dry machining is popular in machining aluminium alloys”

- Gautam K Ahuja,
Managing Director,
Dormer Tools India

What are the latest developments in the tooling industry to meet the challenging requirements in machining difficult-to-machine materials?

To meet the challenging requirement of the difficult-to-machine materials (DTMM), there is a complete range of rotating as well as indexable tools avaliable. For turning applications, Pramet’s new SF, SM, SF2 and SF3 positive inserts provide a secure and dependable option in high temperature alloys. The sharp cutting edges promote low cutting forces which, in turn, prevent work hardening and ensure a quality surface finish.

The PVD coated T6310 grade features a special sintering process, which enhances cutting edge reliability and strength. Its new substrate with intermediate cobalt content provides additional hardness and increased abrasion resistance to offer greater reliability and prolonged tool life. The grade’s triple coating provides durability for higher cutting speeds used when machining stainless steel, heat-treated and hardened materials.

In milling, the M6330 grade has been developed specifically to achieve longer cutting edge durability and reliability in a range of difficult-to-machine materials (DTMM) with and without coolant. This is suited to adverse cutting conditions, including interrupted cutting. It also 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.

In tapping, solid carbide taps for machining hardened steels and other difficult-tomachine materials are available. Offering performance and productivity, the taps are recommended for machining hardened materials up to 63 HRc, providing high wear resistance and long tool life even at high speeds.

What role does tooling play in the context of machining composite materials that requires different mechanism of material removal?

In the use of carbon fibre-reinforced plastics (CFRP), it is often necessary to machine the components, for example, to make holes, trim the edges, etc, but the cutting of CFRP is often made difficult by delamination of the composites and by the short tool life. The process of machining CFRP consists of a series of fractures, each creating a chip. During machining of unidirectional CFRP perpendicular to the fibres, the surface is destroyed and cracks are formed. If the CFRP is machined parallel to the fibres, the surface is smoother, and the cracks reach only one or two fibre diameters into the composite. During machining of unidirectional CFRP parallel to the fibres, the horizontal cutting force (parallel to the fibres and the cutting direction) is determined by the cutting depth and the rake angle, while the vertical cutting force is determined by the relief angle and the wear of the tool. We can use tungsten carbide, ceramics and even CBN to machine CFRP, but we need to keep the cutting speeds low to about 50 m/min.

What are the trends in dry machining? What would be your recommendations to get the most out of the tooling operation, while dry machining?

In the machining of aluminium alloys instead of dry machining, Minimum Quantity Lubrication (MQL) is used. This consists of a small quantity of lubricant mixed with compressed air, which after coming into contact with the hot metal, becomes vapour. This is very effective in cooling the tool and component, and there are tremendous savings on the cutting oil used.

For dry machining of steel, it is only possible to do in small components, with low depths of cut so that the workpiece does not heat up. Also, for finishing with close tolerances, we need to be careful about the bore size which may reduce after cooling. Another precaution to be taken is that the hot chips will corrode the bed of the machine, and they should be cleared and put on the conveyor belt with minimum time lag. Due to these reasons, dry machining or MQL is only popular in the machining of aluminium alloys and not for steel.

“Tools with high performance are the need-of-the-hour”

- B C Rao,
Managing Director,
Kennametal

What are the latest developments in the tooling industry to meet the challenging requirements in machining difficult-to-machine materials?

The tooling industry is evolving and with the type of materials that our customers are machining, we are constantly developing new grades and geometries to meet the demanding cutting conditions. Thus, tools that provide high performance in machining challenging materials like titanium and other super alloys are the need-of the-hour. Having access to technology that helps remove high volume of materials in the shortest possible time is also important, for which the high-feed cutter is also available.

While machining difficult-to-machine materials, components are usually carved out of the material, so there’s a lot of material waste. The cutting tool, and not the material, absorbs the intense heat during machining, which often causes premature tool failure. As it usually runs at low RPMs, it’s also a slow material to machine. As titanium can be expensive to machine and since it is also highly flammable, it poses potential safety risks. Thus manufacturers need tools that are fast, stay cool, increase output, and complete the job without failure. Kennametal Beyond BLAST™ for milling and turning is a tool that meets this challenge.

What role does tooling play in the context of machining composite materials that requires different mechanism of material removal?

Carbon-fiber reinforced polymer (CFRP) is a popular composite material that has the right mix of weight to-strength ratio, durability, and extreme corrosion resistance. This makes it well suited to aircraft hulls and wings. But while composite layers are strong, they can also wear down a tool’s geometry in minutes and splinter at the edge when machined. Such splintering causes weakness and is unwanted especially on an aircraft hull or wing. Thus, it is important to find the tools with the right geometry, clearance, and coating to withstand composite wear and eliminate splintering.

What are the trends in dry machining? What would be your recommendations to get the most out of the tooling operation, while dry machining?

Dry machining is highly challenging for high temperature materials. However, tools in ceramics are available that are best suited to dry machining. One such product is Kennametal’s SiAlON, which is the toughest ceramic on the aerospace market. Depth-of-cut notching is no longer a limitation for SiAlON ceramics. When notching is severe, primarily with roughing cuts, tougher ceramic grades are applied. SiAlON ceramics has a high thermal-shock resistance than traditional ceramic. KYS ceramic inserts are for high-speed applications in high temp alloys. The multilayer coating offers enhanced chemical wear resistance versus uncoated grades.

“Diamond coating is preferred while machining composites”

- G K Verma,
General Manager – Sales,
YG Cutting Tools Corporation

What are the latest developments in the tooling industry to meet the challenging requirements in machining difficult-to-machine materials?

Every tool manufacturer is focused on materials like titanium, stainless steels, hardened steels and other super alloys. Developments in basic tool materials, coating and tool geometries are on top priority with all the tool makers. Since the tool geometries play a big role, a lot of new geometries are taking the lead in the market.

What role does tooling play in the context of machining composite materials that requires different mechanism of material removal?

For composite materials, the coating plays a big role for the tool life and for the day, diamond coating is the best coating in the industry at present. Apart from coating tools with finer grades of carbide, geometries, which can prevent the delamination are also preferred. End mills and drills for CFRP from YG are some options of such tools. Carbide routers, D-Power CFRP end mills, Carbide dream drills for CFRP are also available.

What are the trends in dry machining? What would be your recommendations to get the most out of the tooling operation, while dry machining?

Dry machining is more suitable in high hardened machining and all the tools and die manufactures prefer to go for dry machining since hardness is the main concern during the machining. We recommend dry machining above 40 HRc hardness and use mist air, which will enhance the tool life.

We also recommend using low depth of cut, higher cutting speed and higher table feed to achieve better performance. The range of end mills and drills from YG can be used in dry machining and perform upto 70HRc hardness. The X-5070, X-Power, 4G range of end mills and dream drills for hardened steel are also popular in this segment.

Image Gallery

  • L Krishnan, Managing Director, TaeguTec India

  • Gautam K Ahuja, Managing Director, Dormer Tools India

  • B C Rao, Managing Director, Kennametal

  • G K Verma, General Manager – Sales, YG Cutting Tools Corporation

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