Source: Manufacturing News | December 1, 2010
Air-Way Manufacturing Company is an OEM specializing in producing a full line of hydraulic fittings and accessories for off-road construction, agriculture, material handling and defense. One of Air-Way’s strengths is its ability to design and build custom hydraulic fittings for its customers with quick turn around.
Over the last couple of years Air-Way has had to explore ways of increasing the efficiency of its manufacturing operations. Troy Newman, Manufacturing Technology Manager, along with Jeff Hanson, Plant Manager, and J.C. Buettgen were put in charge of a project to move all of the company’s secondary operation machining from a total of 15 multi-spindle chucking machines onto newer, more efficient equipment. The previous machines had been performing secondary operations for over 125 different part numbers.
The company wanted to accomplish several goals as a result of this transition: reduce setup time from the previous 8-10 hours per operation, reduce labor cost for both setup and production, establish the ability to run smaller lot sizes to minimize inventory (in the past, larger production runs were necessary to justify cost of the longer setups), reduce perishable custom tooling cost, eliminate the labor involved in subsequent de-burring operations and reduce maintenance cost. Air-Way had eight full-time employees in the secondary operations department plus two full-time maintenance persons.
While each goal was considered important, one overriding factor served as the primary focus for the transition. “If we could maintain the same cycle time on our parts with less setup time, it would be a win for Air-Way,” said Newman. Any of the additional goals accomplished were just a bonus.”
In looking at possible solutions for this transition, Air-Way narrowed its choice down to two options for secondary operations: a rotary turntable type of machine or a turntable CNC mill. After weighing the pros and cons of both systems, Air-Way chose the CNC mill. The company chose the CNC mill primarily because it could provide more flexibility in tooling and workholding options. Many similar parts meant CNC programs could be modified slightly from one part to the next. Another important reason was the possibility of much shorter setups and changeovers. Newman felt the company’s best chances of achieving its goals were with the CNC machine. Another reason was the ability to use more off-the-shelf tooling versus custom tooling with a rotary turntable type of system.
Initially, Air-Way was only looking at one turntable CNC mill to start transitioning all of the secondary work. As it turns out, the company purchased two new turntable mills to make sure they had enough capacity and to make the transition happen more quickly. “I was very thankful we decided on two machines, because they have been running two shifts solid for two straight years with very little down time,” said Newman.
As it turns out, deciding on the machines was the easy part. Deciding what workholding system would be best to manufacture all of the company’s parts on the CNC machine was a much bigger challenge. Air-Way had to answer the question, “What type of workholding is going to give us the best bang for our buck?”
Air-Way decided there were several important aspects of the workholding that were critical to accomplishing their goals.
One, the two CNC mills had to accommodate the production of approximately 125 different part numbers, so the fixturing had to be extremely flexible and modular. Setups and changeovers had to be fast.
Secondly, it had to be automated with either hydraulics or pneumatics because Air-Way was going to require one operator to run both machines. Loading and unloading had to be fast and easy so the operator could keep up with the machines. Newman quickly eliminated standard hand clamping options from the workholding equation because, as he said, “We didn’t want operators cranking handles 1,000 times a day.” Operator fatigue and efficiency were major concerns for Air-Way.
Thirdly, because volumes where increasing on many of the parts, Air-Way had to maximize the number of parts under the spindle in one machine cycle. They had to harness the power of multiple-part workholding to gain the efficiency needed. More parts under the spindle meant fewer tool changes and operator load sequences, both major factors in maximizing productivity.
Air-Way narrowed its workholding down to two choices: a dedicated, custom designed hydraulic system and a modular hydraulic system by PAWS Workholding. Once the engineering started taking place to decide how to fixture and locate all of the parts, it was easy for Air-Way to decide on the system offered by PAWS Workholding. The other hydraulic system being considered did not allow as much flexibility in changing over from one part to the next and didn’t allow for the same density under the spindle.
PAWS offered a hydraulic base unit that allows for interchangeable components on the fixture plate to make changeovers truly modular. The system consists of the PAWS Hydraulic base and a fixture plate with sixteen individual 2″ machinable vise jaws. The Sixteen Station Multi-Vise is a standard fixture plate option offered by PAWS Workholding. Air-Way, with the help of PAWS Workholding, engineered removable fixed jaws on the fixture plates for all of the variations of parts the company needed to manufacture. Air-Way ended up with about two dozen sets of jaws that could accommodate all of the various stock sizes and blanks they needed to run.
The jaws can be switched in minutes, so changing from one part to the next now takes Air-Way 20 minutes. Air-Way is able to get as many as 16 parts under the spindle on one pallet with the PAWS System. Most of the machining during the secondary operations is drilling and circular interpolating holes. Another major benefit that has come unexpectedly to Air-way is a huge reduction in scrap rates during setups. This benefit was not listed in their primary goals and has been a pleasant surprise to the transition team. The fixturing was designed to be modular and to locate with repeatability. Now, first pieces come off the machine in print with very little variance from one run to the next.
Air-Way has now been using the four hydraulic base systems from PAWS (two on each machine) for two years with the modular top plates and realizing all of the company’s stated objectives and goals in spades.
All of the secondary operations are now being completed with two machine operators (one on first shift, one on the second) versus eight operators in the past. Setups and changeovers have gone from eight hours to 20 minutes. Air-Way can run any desired lot quantity because the changeovers are so much quicker. Much of the tooling used on the CNC mills is standard, off-the-shelf endmills and inserts.
By using automated clamping, operator fatigue is not an issue. Air-Way no longer has the extra labor in de-burring parts because of the ability to circular interpolate holes with an endmill on the CNC mill, leaving no burrs. The maintenance cost on the two CNC mills is greatly reduced compared to maintaining 15 multi-spindle machines.
Newman also incorporated one other useful advantage in using a hydraulic clamping system. Pressure sensors were installed into each machine to check the clamping pressure before each operation. If the pressure is not at the appropriate level, the CNC machine will not cycle start. Newman said, “We have eliminated operator mis-loads completely, there is no more forgetting to clamp parts. Anytime human error can be eliminated from the process, it’s a good thing.” Air-Way also checks to confirm that the right pallet is loaded into the machine to run the right program; if not, the machine will not cycle start.
Air-Way’s transition of its secondary operations from the multi-spindle machines onto the CNC mills using PAWS Workholding has been an amazing success, the company said. The transition took about six months, and there were many long days for Newman and the transition team. The return on investment took about a year, but Air-Way is now reaping the rewards of all of its efforts.