Repair of indexable tools

Old-fashioned manual machine tools are far from meeting the needs of repairing indexable tools. In order to restore damaged tools with high efficiency and high quality, advanced CNC machine tools and precision measurement equipment are indispensable.

In the past, the repair of cutting tools was something that any machine shop could do. This is no longer the case today. With the increasing complexity of the structure of indexable blade knives and the increasing accuracy requirements, the mechanical equipment required to repair these knives is usually the same as that required for the manufacture of new knives. As a result, many machining shops have become more difficult with old-fashioned manual equipment to repair their tools as they have in the past. Manually repaired tools may look good, but it is difficult to achieve the required cutting performance.

According to Julie Reiling, president of Cemented Carbide Tool Services (CTS) in the United States, “Many companies continue to cut their own internal machining shops. The lack of skilled machining personnel makes it difficult to repair tools on the inside of the factory. Yes, they need to resort to specialized institutions that can repair tools in accordance with a well-controlled, proven program. Repairing tools in an incorrect manner can lead to longer tool indexing times and higher tool change rates, which increases processing costs— - This result is exactly the opposite of what the processing shop is pursuing."

Although many tool repair service organizations have invested in the purchase of advanced CNC machine tools and automation equipment in order to repair the complex indexable tools to a “refresh” state, they still need to rely on all the tool repair work. Hand-made - sometimes not the ideal repair effect - the concept of struggle.

Olaf Klutke, president of GKI, USA, added, “Many small tool repair shops are completely dependent on manual tool repair.” Although in his own company, there are some tool repair jobs still done by hand, more work has been turned into The same automated processing equipment is used to make new tools.

Quality issues

Klutke said that the key issue for tool repair is quality cost. The purchase of CNC machine tools and precision testing equipment requires a large amount of capital investment, but companies that use these equipment have stated that these advanced equipments are necessary in order to restore the more complex indexable tools to a “refreshing” state.

If a shop has already tried manually repairing the tool and the result is not satisfactory, it may choose to purchase a new tool. Klutke said, “This has ruined the reputation of tool repair. Many repair shops have abandoned the repair of damaged tools because the quality of the repairs is not up to standard. As a result, they lost the potential to save millions of dollars in tooling costs. opportunity."

A providing tool repair service. P. Carl Lemke, president of the engineering company, also agreed that the image of the tool repair industry needs to be “restored”. He said, "Unfortunately, there are indeed many bad 'repair workers'. The tools they have repaired look very good, but the user will find that the processing performance of these tools does not meet the requirements."

However, the use of precision testing and inspection equipment as a quality assurance tool repair job can extend the service life of indexable tools. According to Lemke, “For some special tools that are designed and manufactured for a specific process, repairing a damaged tool can save up to 90% of the cost of buying a new tool.” In addition, because repairing an old tool may be more expensive than producing and delivering a new tool. The time is shorter, so it usually saves a lot of time.

Klutke explained that only a small part of a tool with a blade seat is difficult to repair after being damaged, and most other indexable tools can be repaired after being damaged. “Users tend to imagine that a tool cannot be repaired, and eventually it will be surprising to find that this is not the case.” Unrecoverable tools generally refer to tools that have severe cracks that run through the entire tool, bend the tool bar, or severely deform. Most indexable tools can be repaired and can be restored to the initial state multiple times (2-5 times or more depending on the tool type and usage conditions). Some processing plants have used the repair tool for 3 cycles as their own standard.

Significant improvements

Ciling's Reiling pointed out that in the past decade, there has been a significant improvement in the processing equipment used by tool makers. She said, “High-precision indexable cutting tools with modern tool holder technology place higher demands on their repair work, precise machining control and more important precision tool detection are essential. In order to completely repair the tool without destroying Or to sacrifice the original integrity of the steel used by the tool manufacturer, the correct control must also be implemented. Changing the integrity of the original tool steel will jeopardize the cutting performance of the tool, regardless of the level of precision. In the entire tool repair process, must Consider and control the accuracy of the tool and the integrity of the steel."

According to Dan Ryan, head of tool repair at NTM, the repair of indexable tools must meet stringent accuracy requirements. "In view of the tighter tolerances of the workpiece, it is essential that the repaired tool achieve the same level of quality and dimensional accuracy as the workpiece to be machined.

Regarding part tolerances, Jim Leigh, owner of Pyramid Rebuild and Machine, a machine tool revamping, refurbishment and remanufacturing company, believes that "tool accuracy is critical because as the machine becomes more sophisticated, the size and shape tolerances of the workpiece become more The harsher it is, in many machining shops today it is common practice to require cutting tolerances of a few tenths of a millimeter, which in the past could only be achieved by grinding."

Leigh pointed out that the success of tool repair usually depends on two key variables: the quality requirements of the workpiece and the number of workpieces that the repaired tool must process. "If one of these two variables is demanding, the shop may need to select a professional organization with advanced equipment to repair its indexable tools."

Change tool structure

Changing the tool structure makes it possible to save more on tool repair. The entire solid carbide tool maker, Specialty Tools, is also engaged in the repair of worn or blunt hardened tools. The company's president, Jerry Plummer, pointed out that "a trend in cutting machining is to use multi-functional composite tools that can reduce the machining time and reduce the number of tool changes, such as multi-diameter plunge cutters." Because the compound tools are often dedicated tools, and The price for buying a new knife is more expensive than a standard single tool, so the shop's enthusiasm for repairing such tools is even higher.

Plummer said that the skills of the tool repairer are just as important as the equipment they use. “Machine must be repaired by a technician who has technical qualifications and can properly use appropriate machining and inspection equipment. However, whether or not a tool needs to be repaired on a CNC machine tool is a decisive factor in the complexity of the tool and the number of tools that need to be repaired.”

High speed scrap?

The processing batch, the complexity of the tool, the machinist's skills and experience all together determine whether the tool should be manually repaired or whether the tool should be repaired on a CNC machine. Leigh said, “Many mass-produced parts are machined on automated equipment. In this process system, if there is a problem with the tool, a large number of workpieces will be scrapped at a very fast rate. The higher the degree of automation of the process, The more reliable each component of the process must be. Of course, the tool is also one of these components. Indexable tools that do not meet the technical requirements will wear faster."

In high-productivity machining, because the chip load of one blade and the next blade is irregular or inconsistent, the indexable cutting tools will fail faster. If the tool does not run properly due to a failure to repair properly, some blades will cut a larger diameter than the other blades, cutting more material per revolution than other blades. Leigh pointed out, "All of these problems will shorten the blade life. In any process, especially in high-speed, automated processes, this will quickly consume a large number of carbide blades, not to mention the increased downtime needed to solve problems and replace blades. ."

Thoughtful plan

Ciling's Reiling believes that the best results can only be achieved if the tool repair work is carefully organized and made part of the workshop system. This plan includes the collection, distribution and training of operators. "We work closely with our customers to organize a well-structured tool repair program in their factories, which emphasizes that by using repaired tools instead of buying new tools, we can reduce tooling costs and create value. Significantly reduce tool inventory requirements and further reduce production costs."

For example, CTS implemented a repair program for indexable tools (bits, cutters, and toolholders) at a large aircraft manufacturer. CTS first fixes the indexable tool that has been damaged by the manufacturer, and if the user needs to repair the tool, submit a repair order. It is then repaired by the CTS according to the tool's original specifications. By repairing a damaged indexable tool, the manufacturer saves more than $150,000 in tooling costs per year compared to buying a new tool.

GKI's Klutke also agreed that part manufacturers should develop a comprehensive plan to ensure that all repairable tools are repaired to minimize tooling costs. He said, "First of all, we need to establish a collection system for end-of-life tools throughout the entire plant. In the past, scrapped tools were often thrown into the waste container and they were rarely considered for repair."

Klutke said that although the most important reason for repairing tools is to save money, the most important goal pursued when repairing tools is quality. In general, a repaired indexable tool costs 50%-85% less than buying a new tool, but if the cutting performance of the repair tool does not reach the level of the new tool, this cost savings is meaningless . Klutke said, "In fact, if a repaired tool fails prematurely, or if it is not repaired to the correct size and precision, then its ultimate cost may be higher than buying a new tool." GKI guarantees that The repaired tool will have the same good cutting performance as the new tool, and its expected service life will not be affected.

Although tool repair may be cost effective, NTM's Ryan cautions users of potential tool repair services to investigate the qualification and level of tool repair companies. In recent years, many tool repair companies have emerged, but "users must always be cautious. Not all tool repair companies can do this job at a high level."

Lean repair

Global competition and lean production are the two major driving factors for tool repair. Arthur Ellis, a tool engineer at Brewer Automotive Components, said that a few years ago, the shop had scrapped worn-out tools more often than not. "We saved about 50% of the cost by repairing tools compared to buying new ones. I Adhere to the advice of a tool repair company - the tool is recycled three times after it has been repaired." His advice to other users who want to repair more (rather than discarded) tools is simple: "Create a tool repair plan; choose Certified tool repair service provider; uses quality-proven repair tools; ensures the correctness and timeliness of tool drawings."

GKI's Klutke pointed out that to carry out tool repair work, we must first develop a tool recycling system that covers the whole plant. "The tool repair company can provide a variety of services to facilitate the implementation of the repair process. For example, we can provide off-site inventory management of tool recycling bins, shipping containers and recycling tools." He added that the workshop that considers the development of a tool repair plan You should also carefully examine the repair equipment you plan to use.

According to Plumber from Specialty Tools, depending on the tool type and complexity, it may be necessary to mark the repaired tool. The tool repair company should also provide a quality inspection certificate for the repaired tool. This requires appropriate inspection equipment and fixtures as well as machinists who have extensive knowledge of the various indexable tools on the market.

According to Reiling of Cemented Carbide Tool Services, a tool repair shop should also be ISO certified and be able to implement precise quality control including management of relevant technical documents and inspection procedures. She said, "A tool repair shop that can guarantee quality requires sophisticated equipment, formal fixtures, and well-trained operators. Understanding the accuracy requirements of the tool and maintaining the integrity of the tool material are critical to the repair process."

Reiling pointed out that testing is particularly important for the repair of certain tools. For example, a U.S. car manufacturer uses a special indexable tool chuck to machine certain parts. This type of inlet chuck is expensive, requires high precision, and has a long lead time for ordering new chucks. Carbide Tool Services has developed a remediation plan for these tool chucks that can now save users more than $200,000 in tooling costs per year. According to the remediation plan, CTS will conduct a rigorous inspection of the collet during the remediation process to ensure the quality, and the inspection process is completely consistent with the user's acceptance inspection process. In order to shorten the delivery time, the user must submit a comprehensive order, so that the cutters that need to be repaired can be repaired as soon as they reach the CTS company.

All tool repair services are not static, and even if your shop has had an unpleasant experience with tool repair, consider again how to perform tool repairs - including a field visit to a potential tool repair service provider - maybe still Significant. Expensive indexable tools are critical to the success or failure of processing and cannot be entrusted to anyone.