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CUTTING TOOLS Optimising the machining process with right cutting tools

Oct 18, 2019

To cost-effectively machine excellent-quality parts, many manufacturers take on a similar path, starting with cutting tool selection and then resolving any difficulties that come about. The Viewpoint section finds out what are the factors for the correct selection of cutting tools for a definite application, how the performance of cutting tools can be maximised and the recent trends in machining and cutting tools.

Tool metallurgy and geometry with life needs to be understood - Jagannath V, Business Head, m2nxt - A BFW subsidiary

The machining process' initial steps would be based on the component metallurgy, material stock and the finish tolerance of the component. Of course, the machine specification needs to be in line with the machining process. Secondly, the work holding of the component and the yield due to machining thrust needs to be understood as we witness components are moving towards aluminium alloys which are very vulnerable to work holding. Besides, taking the parameters for the right selection of cutting tools for a specific application, tool metallurgy, reach, completion of operation and the geometry with life need to be understood based on the customer need.

Inspection through automated gauging can achieve 100/10/0 ppm with a planned implementation. In such an event the component machined is very critical; each process can be digitised by RFID tags, which can record all the cutting and inspection parameters for every operation on each component. Recalls on components due to failure can be related on cutting/tolerance parameters captured due to digitalisation and the corrective action can be instantaneously implemented back in the cell/line. In order to maximise the performance of cutting tools so as to improve productivity, minimise downtime and reduce cost, we always recommend the customers to go in for tool probing & automatic component inspection with the customised gauging station designed and developed by us. This results in improved productivity (minimum rejections) and hence, reduced cost. Depending on the affordability of the customer the process can be tailored.

The mantra is to increase efficiency and reduce wastage - Gautam K Ahuja, Managing Director, Dormer Pramet India

The trends in machining and cutting tools are very dynamic in nature, with new developments happening all around. Digitalisation is more on the manufacturing area, where all machines are linked to the main server, and we have flexibility of manufacturing. The mantra today is to increase efficiency in every process and reduce wastage/downtime, etc. to be ahead of competition.

For any optimisation, the precondition is that the quality parameters of the job should be met and the process capability curve must be followed. Cutting tools play an important role while defining a strategy for machining process. It becomes more important when all the new materials like, Ni and Ti based alloys, composites and other difficult to cut materials are coming in. The right selection of cutting parameters, grades and geometries not only does efficient machining, but also helps maintain the geometrical tolerances of workpiece, improves productivity and maintains the cost per component ratio. The objective of any tool selection is to determine several parameters, such as, toolholder, insert, cutting conditions, type of the coolant (if required) and total cost of machining. Thus, we need to optimise the parameters so as to strike a balance between productivity and tool life.

Also, choosing the right feeds and speeds when machining demands a delicate balance between productivity, part quality and tool selection. If one pushes machines and cutting tools too hard, the time needed to change tools might eat up any productivity gains — and machinists might burn through their tools too quickly. Hence, finding the sweet spot of optimal tool life and productivity can seem like an elusive quest. However, we need to take care of five things – proper programming, selection of the right geometry and grade amid the labyrinth of available inserts, optimising the depth of cut, applying the right cutting speed and feed to have a high productivity and tool life.

Most failures in machining are due to the abuse of cutting tool - Kashinath Patnasetty, Head – VAS & Application Support, Ace Designers

A major point to be considered for optimising machining process is to eliminate operator intervention while machining, and less or no intervention of operator will help one get higher productivity and efficiency. One needs to produce a few batches of components with average cutting parameters and record the trends. This will help one to take action for further improvements and optimise the process with ensuring less or no operator intervention.

Optimising machining process not only depends on using higher cutting parameters, but also requires one to consider work holding, tool contact time and effect of tool wear on quality and esthetic of component machined. Each operation for the given part must be defined with a sustaining machining technique. Most failures and operators interventions in machining are due to the abuse of cutting tool, thanks to the abnormal movement of tools at critical areas and abuse of work holding due to abnormal input variations and clamping force/method. Hence, crucial parameters for the selection of right cutting tools are considering optimum cycle time, competitive production costs, improved quality, performance and longevity of machines.

However, assuming we are using the right tool and tool holding system, the major contribution for performing high is by right cutting methods; in most cases, we tend to ignore the possibilities of tool abuse at tool entry/exit, tool percentage of contact at corners, etc. Only by periodic reviewing and revamping of the programs and processes can one eliminate the accumulated inefficiencies to minimise downtime and reduce cost. What are needed are resources, like best CAD/CAM, which can simulate and generate efficient program with an optimised tool path. So, we need more synergy with machine tool builders and cutting tool manufacturers to extend a comprehensive support for machining industries. Automation is still a challenge unless we establish a process with zero operators’ intervention and ensure quality with post process or in process gauges.

A digital portal helps customers select the right cutting tool - Rajesh Gupta, Deputy General Manager, Seco Tools

The complete know-how of the component material and machine to employ the best tool and the strategies to be used are key when considering process optimisation. Performance, reliability and consistency are the factors to be taken into consideration while selecting the cutting tool. The selected tool should deliver its best in a more predictable and defined way; it should be application-specific and according to the workpiece material. The right cutting parameters (cutting speed, feed and depth-of-cut) with the right strategy not only helps increase productivity but also minimise the machine down time and tool failures, thus reducing the cost per operation. The proper discipline to be maintained for the tool changes when it is worn-out rather than running it further, which results in tool breakage and increases the down time and tool cost. Anti-vibration system (steadyline), high coolant pressure (JET Stream) and the latest available coated grades and geometries also help in trouble-free machining and boost the productivity. Advance cutting tool materials, like PCBN and PCD multi-fold the production
outputs and reduce the operation cost.

The right selection of cutting parameters, grades and geometries not only does the efficient machining, but also helps to maintain the geometrical tolerances of workpiece, improves productivity and maintains the cost per component ratio. As the right selection of cutting tool and cutting parameters are the key for successful implementation, digitalisation is now playing an important role as well. A digital portal helps the customer in selecting the right cutting tool and the parameter based on the workpiece material and strategy.

Each day, the cutting tool industry is facing new challenges in terms of new workpiece material, more complex shapes, productivity improvement, the un-manned machining, with geometrical tolerances getting closer. For efficient machining, these materials require the latest and special carbide grades, coating and geometries; new advanced materials, like PCBN, PCD and ceramics are becoming the best alternates for improving productivity and machine efficiency.

Coating specification is important regarding tool material - Ramesh Kumar Agarwalla, Jt Managing Director, Kyocera CTC Precision Tools

We need to check a critical point for the machining process required for its practical application, such as, dimensional tolerance, surface finish value or for its viewpoint of productivity and so on. Then, we consider how to improve such points by selecting suitable tools. In addition, one should understand workpiece material well, so that one can apply proper grade of tools for each process. Speaking of grade of tools, it is one of the most important points for the right selection of cutting tools for a specific application, such as, carbide, cermet, CBN, ceramic, and so on. Coating specification is also important regarding tool material. As for application, cutting conditions are critical, such as, cutting speed, depth of cut, federate, etc.

When it comes to maximising the performance of cutting tools so as to improve productivity, checking each process carefully helps, so that one can find out which one is a bottleneck preventing it from improving productivity. For example, bad chip control often decreases productivity by stopping machining process to remove tangling chip, or worse, surface finish makes it difficult to increase productivity due to lower federate required. After understanding such a critical point, we can focus for it to improve by selecting suitable tools and optimised parameters.

There are also several trends I see coming up in machining and cutting tools, such as, cutter with optimised shape and light weight by 3D printing technology, new tool path enabled by a new design of tools and a combination with machine and digital processing diameter management for boring bars. As for grade, ceramic sometimes shows better performance than conventional CBN for hard parts machining. Also, CVD coated cermet performs well against carbide grade.

Cutting tools play a crucial role in defining the strategy for machining process - Prashant Sardeshmukh, Vice President & Director, MMC Hardmetal India

Optimisation is either based on cut time or cost per component criteria. Steps under proactive analysis of machining operation involve proper study of cutting conditions, geometry of the workpiece and its metallurgy for selection of proper cutting tools. The other factors include study of depth of cut, selection of cutting speed & feed, which can be made using constrained or unconstrained mathematical optimisation methods. The workpiece machining at times causes tool wear and sudden breakage, which leads to machine downtime. These issues can be addressed by following the best manufacturing practices. The most important thing is to choose the right feeds and speeds, when machining requires a good balance between productivity, quality and consistency.

In today’s world, rapidly changing market demands require special efforts to implement new technologies at a competitive price, stipulated time frame & user-friendly ways. This is one of the biggest tasks before the cutting tool industry. Cutting tools contribute a very small amount of investment to the overall production process but they play a crucial role in defining the strategy for machining process, especially when new materials, like Ni and Ti based alloys, composites and other difficult to cut materials are used. Selection of the right cutting tools is based on the material to be machined, available power on the machine, fixture stability, machine dynamics etc. We develop the tools well in advance which the industry is going to need in the future.

Image Gallery

  • Jagannath V

    Business Head

    m2nxt - A BFW subsidiary

  • Gautam K Ahuja

    Managing Director

    Dormer Pramet India

  • Kashinath Patnasetty

    Head – VAS & Application Support

    Ace Designers

  • Rajesh Gupta

    Deputy General Manager

    Seco Tools

  • Ramesh Kumar Agarwalla

    Jt Managing Director

    Kyocera CTC Precision Tools

  • Prashant Sardeshmukh

    Vice President & Director

    MMC Hardmetal India

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