GLOBAL TOOL DETERIORATION ANALYSIS (GTDA)
The path to operational excellence starts here
Cutting tools are by their nature consumable; they wear until they are no longer effective. A traditional approach to metal cutting tool management employs wear analysis alone, focused on manipulating tool materials, geometries and application parameters to improve part output and tool life in a selected operation. Maximizing the efficiency of a facility’s entire manufacturing process, however, involves consideration of a broad range factors in addition to tool wear. It is essential to examine cutting tool wear or, more broadly, tool deterioration, in light of the overall or “global” manufacturing process.
Global Tool Deterioration Analysis (GTDA) goes beyond basic measurement of tool wear to include tooling-related considerations such as time spent in tool manipulation, problems other than wear, production economics, shop organization, personnel attitudes and assumptions, value stream management, and total manufacturing costs. GTDA is based on regular evaluation of a large number of a shop’s used cutting tools randomly selected to construct a comprehensive picture of their contributions to the facility’s manufacturing efforts overall.
The Global Manufacturing Process
Study of tool wear usually is limited to a single tool employed in a specific machining operation. However, to gain maximum benefits, it is essential to examine tool wear or deterioration in relation to all tooling in a facility’s manufacturing processes. The manufacturing process begins with acquisition of raw materials and planning that involves utilization of human intellect, technological resources and capital investment. The process advances through value-adding and value-enabling activities but may be restrained by waste-producing events that result in the loss of money, time and intellectual resources and consequently reduce part quality and yield. Output is measured in terms of part quality, the quantity required and desired production time and cost.
Focus On Process Before Results
Many manufacturing process analysis efforts focus on reviewing end results in relation to tool life and part output without thoroughly examining the process itself. Problems related to cutting tools, but not directly to tool life, may be missed and create production bottlenecks. For example, burrs typically are not related to tool life, but their occurrence interrupts the manufacturing process because another operation must be developed and implemented to remove the burrs.
Burr formation is, however, related to tool geometry and application parameters and therefore must be considered in tool deterioration analysis. Tool breakage, another problem not usually related to tool wear, does involve tool material, geometry, application parameters as well as machine tool factors.
Considerations Beyond Tool Wear
Global tool deterioration analysis supplements initial measurement of insert edge wear with analysis of the tools’ role in Cost of Goods Sold (COGS) totals, Single-Minute Exchange of Die (SMED) analysis, Value Stream Management (VSM) results and Overall Equipment Effectiveness (OEE) percentages.
The most basic tooling-related economic consideration is clear: tools cost money. Figure 4 presents the cost of various elements of the machining process and totals them as COGS. This data enables a shop to compare and contrast the various elements of production costs, with an eye on finding candidates for cost reductions that will boost operational profitability.
Another tool-related economic factor is that tools cost time – the time involved in manipulating tooling outside of actual machining operations. Time spent in tool changeover and setup is analysed via SMED analytical techniques that also provide a view of costs beyond those generated by tool wear and replacement. Part of that expense is incurred in acquiring and organizing tooling and mounting it and loading programs into the machine tool.
OEE determines how much of the available manufacturing time is used effectively. OEE analysis points out losses, benchmarks progress and improves productivity by eliminating waste. The total time available for production is identified, then the analysis subtracts planned downtime, unscheduled breakdowns, changeovers, minor stops and lost speed, and scrap and rework to arrive at effective machining time expressed as a percentage of the total time available. A 100 percent OEE – a noble but practically unattainable goal –means a part is produced in the specified quality, as fast as possible, with no wasted time.
VSM analysis illustrates the need to balance performance improvements among all the elements of the manufacturing process. Figure 5 is a graphic representation of the effects of improving the performance of one element of a system without improving others. Think of individuals rowing a boat. Higher performance by one rower would actually hurt the boat’s overall performance.
Improvements in parts of the process must be made in view of their relation to production volume and variety, workpiece material characteristics, part geometries, machine tool and fixturing requirements and other considerations to achieve and maintain a manufacturing operation that is in balance overall.
Global Tool Deterioration Analysis
GTDA is basically a simple process. The cutting edges of a large number of randomly chosen tools from throughout a shop are examined one edge at a time to determine which edges are worn. The wear is classified according to its type and amount. Traditional tool wear analysis concentrates on one tool in one operation; GTDA gathers information about tool wear and other tool-related issues from the entire shop, then applies COGS, SMED, VSM, OEE and other analytical tools to compile additional data that will guide planning and implementation of improvement programs.
To be successful a shop must have the discipline to begin a GTDA program and, equally important, continue tool examination and data analysis on a regular basis. Another form of discipline – honesty – is required as well. A shop must honestly and objectively accept the results of the analysis and be willing to act on the findings without regard to shop traditions and politics or unsupported opinions regarding tool application parameters.
Tool wear is inevitable and managing it is essential to achieve successful machining operations. However, tool wear is just one example of the many influences of cutting tools on the efficiency of a facility’s overall manufacturing process. GTDA goes beyond wear analysis of single tools to include all the tools in a shop as well as a wide range of significant tool-related influences outside the cutting process.
GTDA: Why and How
At the peak of the era of high-volume mass production of individual parts, tool wear was simply measured, manipulated and balanced to maximise tool life and part output. As manufacturing strategies have progressed into a more just-in-time production of near-custom components, tool wear by itself has become a less central element of the manufacturing process overall.
Seco Consultancy Services continually analyse ongoing manufacturing evolution and has developed its “NEXT STEP” production model to deal with the continual changes in the manufacturing industry. The NEXT STEP model is based on the four key standards of machining, namely cost efficiency, time efficiency, quality and yield. Next Step enables manufacturers to set and meet machining standards for themselves through analysis of waste production, machining process technology, tooling and workpiece material science, production economy and yield, and the critical role of people and leadership in their operations.
Global Tool Deterioration Analysis is a key component of overall manufacturing process evaluation and improvement. By examining a random selection of tools covering all machining areas of a facility, then applying a variety of production measurements, a manufacturer gains a broad understanding of the role that tooling plays in the entire machining process. GTDA helps shops discover where tool performance can be improved to boost productivity, and where tooling-related issues may be creating time- and money-wasting bottlenecks in the manufacturing flow.