The transformation of CNC machining system

After introducing the CNC machining system into the manual production process in the past, the entire processing plant has embarked on a lean manufacturing path and now has a continuous flow production line.

Fig. 1 This combination tool module is equipped with a number of pre-adjusted tools. The user only needs to install the tool shank on the tool board and then start the work.

Clippard Instrument Laboratories, Inc. is similar to an intermittently-produced processing plant. From the point of view of the nature of its parts production, the varieties are very mixed and the production volume is also low. A total of 5,000 standard parts are included in the company's catalogue of product catalogs. This means that for pneumatic manufacturers, it means that it is difficult to apply “real” lean production processing units. For this reason, the company applies its own lean brand to the production process to meet the increasing demand. Especially for the company's secondary operations department, this is particularly reflected in this, and began to develop to the CNC processing system. Through an appropriate combination of CNC turning machining equipment, group control tools and professionals, the pneumatic device manufacturer has created processing units with added value, and these processing units have now become a distinctive feature of their lean production.

Clippard manufactures pneumatic and electronic control devices. The processed products include cylinders, control valves, electronic valves, combination valves, standard parts and a range of industrial hoses. The founder of the company was Mr. Leonard Clippard. The company started business in 1941 and its business is now run by its sons, Mr. William and Robert Clippard.

Mr. Robin Rutschilling, Production Operations Manager at Clippard, said: "It is not surprising that there is an employee who has worked in the company for 30 years."

The company's components are mainly used in the dental and medical industries as well as in general automation, packaging, liquids, and logistics transportation. For example, the suction valve it produces is made up of parts such as a straw used by a dentist. It can be used to rinse the teeth and wash away the stain without splashing water on the patient's body. The electronic valve produced by Clippard was also used in the hospital's automatic blood pressure machine.

Fig. 2 This processing unit consists of 3 independent manual machine tools. It is mounted on a flatbed with wheels so that it can be moved to work near the secondary operator arbitrarily.

Manual transformation

For Clippard, in order to be able to immediately meet the needs of a series of small parts production, they decided to upgrade their turning operations to CNC machining technology. Mr. Jim Shaw, CNC setup/programmer at Clippard's secondary operations department, can verify the changing nature of turning in the shop floor.

Mr. Robin Rutschilling said: “About 6 years ago, when I started working here, the production volume was still relatively low, but the variety of workpieces was large. This required continuous debugging settings. I had to constantly These pieces are switched back and forth."

The requirements for precision machining of parts have also become higher and higher, which has further made the previous production equipment a problem. When facing the choice of buying new equipment or renovating some of the old manual machinery that was abandoned in the basement, Mr. Clippard chose both.

Through consultation with Mr. Mike Pasko, Sales Engineer of Richlin Machinery/Omniturn, the workshop believes that it is feasible to retrofit and renovate manual equipment, which is much cheaper than the cost of purchasing a series of CNC new lathes. In June 2000, Clippard began retrofitting one of its hand-operated lathes, an electro-hydraulic machine originally manufactured by Hardinge. Most machine tools were reworked and an Omniturn machine was installed on the original bed.

Mr. Pasko explained: "We removed the original electro-hydraulic control system and turret mechanism on the machine tool, because these components are no longer needed, but we still use the original machine's frame, bed and spindle box with spindle."

The workshop also purchased two Omniturn GT-75 used CNC lathes. Later, three more refurbished processing equipment and another GT-75 lathe were added, all of which made it easier for the secondary operations department to complete certain processing tasks. According to Mr. Rutschilling, CNC machine tools played an important role in several frontier processing businesses in this sector.

He said: "We have managed to make these machine tools used to machine workpieces that were previously impossible to machine at all. The accuracy of machining of parts is also very obvious. In fact, the machining accuracy of these CNC lathes has exceeded the accuracy required by our customers. ”

Now, Clippard can make some changes in the process without interrupting the planned production. It can also create the prospect of lean production. While the lathe is running, the employees can increase the output value by completing the secondary operations business.

As Mr. Shaw explained, shortening the production cycle itself has great significance. He said: "If we can save 1s time per part machining, then we can process 50 more parts a day. This means that customers can get more parts faster."

According to Mr. Pasko, the Omniturns device is ideally suited for the processing of 1/8 to 1 inch (1in = 25.4mm) parts by the Clippard machine tool. The revamped manual machine and GT-75 lathe used not only group control tools but also Omniturn control systems.

In the turning area, the processing capabilities of the machine tools are basically the same, and the shop can process any kind of parts on any machine. In general, both the old machine tools and the new machine tools can machine aluminum and brass, but they are mainly used to process the internal components of combination valves and the body of a toggle valve. Due to the use of standardized group control tools, Clippard can comfortably manage frequent commissioning cards.

Bring everything together

The arrangement of group control tools allows the tool to quickly change from one type of workpiece to another in a variety of ways. For example, when machining a workpiece, three tools are required. If the workshop receives a batch of workpieces that are in urgent need of machining, it needs to be processed by a tool. Mr. Shaw described how he managed to make the processing equipment run as part of the order.

He explained: “Because there is an open slot in the shank, I can call it 'Cutter 4' and modify the program after changing the offset of 'Cutter 4' and changing the chuck of the second part. , I can process the urgently needed workpiece first, while the other workpiece is still in the clamped state.After removing the 'tool 4', I only need to call the first part of the program, and then change the chuck, you can re produce."

More importantly, the entire tool bar - the entire set of tools - can also be replaced. With this modular tool module unit, the operator can pre-adjust the tool for a specific part and mount the tool shank on the tool board (with the tool on the tool board), so that everything is ready to work. . No time is wasted when changing tools.

It is necessary to reserve a certain amount of tool space on group control tool lathes. In order to make full use of the limited space, the workshop uses the Omniturn Multibar multi-tool turning system, which consists of a quick-change tool holder and a multi-functional insert. This type of insert saves space because a tool can perform multiple machining operations. For Clippard's machining, this type of tool can complete turning, slotting, and face machining operations while occupying only one tool slot.

Mr. Pasko said: “The number of tools required, the geometry of the parts and the operations required in this application area are perfectly suited for the group control operation of the combined tool. At Clippard, turning a typical part is only 5~ 6 tools, so this is very important. If you need a considerable number of tools, you may need deep hole drilling, so it may be more appropriate to use a turret tool."

Figure 3 During the machining cycle of the GT-75, the operator can concentrate on secondary operations such as rolling, chamfering, burrs and drilling.

Liberalization of production

Makes the settings easy to manage, giving operators and commissioning staff great mobility. Operators are no longer limited by manual equipment. They have greater freedom to install other machine tools or perform other value-added activities.

A new type of combined processing unit consisting of three independent manual machine tools exploits this superiority of freedom. The machine is mounted on a flatbed with wheels and the machining unit is close to a row of CNC lathes. In the 45 to 55s production cycle required for CNC turning operations, the operator can use this processing unit for secondary operations such as broaching of grooves, drilling of cross holes, or countersinking of parts on lathes. . Operators can also use micrometers, calipers, and functional gauges for inspection. In fact, the operator does not even need to walk in the workshop. Mr. Shaw says that sometimes he can move a wheeled mobile machine near a specific lathe so that the operator can perform various operations on a specific part without walking in the workshop. In a shift, it is often possible to complete the processing of more than 100 parts and wait for shipment.

Tools can also be placed on flatbeds that can roll. Mr. Shaw is responsible for the debugging of the tool. He can push the flatbed car from the machine tool to the machine tool and quickly complete the debugging task of the tool. As the time taken to access the tool is shortened, he can concentrate on the programming work, delegated work, and substantive debugging work of the workpiece. The flatbed includes all the inserts, drills, combination handles and special chucks he has configured.

Mr. Shaw explained: “With this simple solution, we can save a lot of time in a year. In this way, we will not waste the time it takes to move back and forth between the worktable and the workpiece.”

This will not only facilitate the completion of value-added activities, but also facilitate the acceleration of continuous flow operations. This means that the production and movement of a project or a small group of projects can be achieved as seamlessly as possible by a series of steps, so that the workshop is better equipped to carry out small-batch production, with fewer obstacles. Completion of production tasks can actually create more value.

For Clippard, automation is a major factor in promoting continuous flow operations. This process was further optimized by Mr. Clippard, who has installed their own developed air-cutter feed device, aerodynamic chip blowing device and part catcher into new and retrofitted machine tools. This type of technological innovation also allows these machines that perform secondary operations to use their open functions for initial operations.

For example, Ms. Sharon Flaum's workstation (see Figure 4) basically only applies to the machining of one part, the toggle body. While the GT-75 lathe can perform groove machining, section machining, thread machining, drilling and knurling on this specific part, Ms. Flaum is mainly engaged in rolling, chamfering, deburring and Drilling processing.

Figure 4 Ms. Charlene Watkinds, machine operator, is standing in front of the deburring workstation that is in line with Brother Brothers's machine tools. She needs to walk between this workstation and the chamfered area (see the small photo on the right) as the machine tool needs to mill and drill the ventilation holes and toggle holes on the manifold.

The same lean processing methods are used in other parts of the plant. Current CNC milling machines are equipped with an alternative processing station for chamfering and deburring.

At the same time, ideas continue to move forward. Now, the overall goal of the company is to continue to develop processing units in each processing department, not only to integrate it into processing operations, but also to integrate it into production and assembly. The company claims that their next step was to introduce a "real" lean processing unit at its Fairfield, Ohio facility. This processing unit will be used for the company's cylinder head machining - including the entire process from beginning to end.