Automated material handling helps boost clutch output: new plant system helps Warner Electric Brake & Clutch Co to up production from 6,000 to over 10,000 units a day, and to cut scrap to less than 40 percent of previous rate.
A 1979 investment to boost production of automotive air-conditioner clutches--and also to improve quality and wring out costs--is proving to have been a wise decision by Warner Electric Brake & Clutch Co, S Beloit, IL.
Even though completed just as the US automotive industry slid into the doldrums, and although producing at less than capacity, the improved facility is said to be enabling Warner Electric to gain market share, fend off imported parts and weather the recession better than most automotive industry suppliers.
10,000-part capacity desired
In the late '70s, the market for automotive clutches looked rosy. The existing Warner Electric facility was running flat out, producing some 6000 clutches a day, 7 days a week, over 3 shifts. New contracts at that time were expected to require a boost in production to 10,000 a day. Outputs of 15,000 or more a day were forecast for the mid '80s.
In this atmosphere, Warner made a quick review and estimated that a linear expansion of its existing manufacturing methods to achieve a 10,000 unit a day rate would require a 50-percent addition to the air-conditioning compressor-clutch facility, and a capital expenditure of $8 million for new equipment.
Hesitant at spending so much money, and knowing that a linear expansion would not solve troublesome cost and quality problems, Warner Electric asked Ingersoll Engineers Inc, Rockford, IL, to review its plans and make engineering recommendations.
The resulting system, along with a largely Warner-directed quality-control program, yielded:
An increase in maximum capacity to 10,000 parts a day within the confines of the existing 20,000-sq-ft area. The company uses two 10-hr shifts, and made an equipment investment of only $5 million.
Actual production in Jan 1982 of 7000 units a day in two 8-hr shifts using 94 shop employees and 4 supervisors. This contrasts with the previous 6000 parts a day in 1978, with 125 shop employees and 8 supervisors working 3 shifts.
A reduction in scrap from 2.5 percent of sales in 1978 to less than 1 percent in 1982.
A marked improvement in product quality, Warner Electric received a $20,000 check from one customer in 1981 for beating the target in a shared-warranty program.
The need to automate
In making its 1979 study, Ingersoll Engineers found that the majority of existing machining, assembly, painting and packaging operations were stand-alone and labor intensive. Material handling consisted of a combination of lift trucks and manual operations.
The recommended system largely called for multispindle machines that would be automatically loaded and unloaded, and include automatic checking and tool compensation. Also, the new system would have automatic assembly, inspection and painting. These functions would be all tied together wherever possible with automated material handling, including buffer storage.
Ingersoll Engineers was hired to implement the assembly, painting and material-handling areas, as well as to assist in the installation of system components. The consultant's responsibilities in those areas were to conceptualize the equipment, recommend vendors, approve final designs, schedule and oversee installation, and train key maintenance and operating personnel.
The photo above shows the automotive-clutch machining/assembly/painting/packing as it now stands. Presswork, unchanged except for the addition of two new presses, is now shown.
A Warner Electric automotive air-conditioning-compressor clutch consists of three basic components: (1) a rotor/pulley (welded assembly plus pressed ball bearing) driven by a car's fan belt, (2) an electrical coil assembly (a wound coil potted in epoxy within a steel shell), and (3) an armature assembly (friction plate, body and miscellaneous parts) mounted on the compressor shaft to engage the friction face of the rotor/pulley when the coil is energized.
Rotor/pulleys are machined and welded on two separate manufacturing lines. One line handles eight different sizes of conventional or double V-belt spun-steel pulleys, either spot or MIG welded to appropriate rotors.
The other line produces one size of a poly-V-belt machined pulley that is inertia welded to its rotor. The rotors for both styles arrive at the lines already blanked, drawn and pierced on progressive dies from 0.220 hot-rolled (HR) C1010 coil stock. The poly-V-belt pulley is machined from C1010 sawed tube blanks.
The field coil is potted within a blanked, drawn and pierced shell of 0.156 or 0.220 HR C1010. The shell is machined, a mounting-plate projection welded to it, the coil is added, and then the assembly is potted.
The armature's friction plate (pierced and blanked of 0.187 C1010) is ground on the line and mounted to a body/hub assembly that is spot welded on the line.
Ingersoll Engineers recommended Ex-Cell-O three-spindle CNC horizontal chuckers for light machining of the rotor parts and coil shells, replacing multispindle vertical chuckers, engine lathes and boring machines.
"These NC machines were new to the market at that time, and were primarily chosen because of their amenability to automatic loading and unloading, electrical-switch reprogrammability for different parts setups and automatic tooling-compensation capability,' commented Al Bohn, Ingersoll Engineers staff engineer in charge of the project.
"We had evaluated these new chuckers and believed them to be capable and sufficiently bug-free.
"The machines could have been supplied with from one to four spindles. We recommend the three-spindle design as best for Warner Electric's production volumes.
"Other important new or modified machines include Bullard 12-spindle vertical chuckers for heavier cutting of the poly-V-belt pulleys, flat grinders, wirebrush deburrer, and MIG, sport and inertia welders,' Bohn said. "To improve weld quality we recommended, and Warner Electric concurred, that the original spot welders be converted to projection weld the mounting plate to the shell.'
Unique buffer dominates material handling
Interconnecting all of the new three-spindle chuckers and most other machines are blue-steel, gravity-feed conveyors and storage elevators. Other conveyors installed include a monorail for spun-pulley degreasing, magnetic belts to move parts up and down the aisles, conventional belts, chain on-end pin for painting, and pallet-type roller for packing. Most of the machines served by the blue-steel conveyors have either load/unload arms of pick-and-place units.
"A unique piece of conveying equipment is an in-line, 16-lane, microprocessor-controlled vertical buffer for storing completely machined rotor/pulleys awaiting assembly of bearings and grease guards,' Warner Electric's Plant Manager Ken Wulf stated.
"We batch machine nine sizes and types of rotor/pulleys, and subsequent assembly operations are designed to be about 25 percent faster than machining to maximize assembly flexibility. It is therefore necessary to store some of the output of the second-shift machining lines during the average half shift that assembly is down.'
Ingersoll Engineers worked with a conveyor supplier (Mallard) to design and construct a 22-ft-high gravity-fed storage tower consisting of 16 lanes by microprocessor-controlled gates. When one lane is full, the system automatically directs parts to the next designated lane.
The control also indicates the type of parts stored in each lane and whether each lane is full, partially full or empty. During the summer of 1982, production volume dictated that six lanes were normally assigned to poly-V-pulley rotors, the remainder to spun-pulley rotors.
Each lane will hold from 600 to 700 parts, or a total of about 10,000 for the buffer. The microprocessor also controls release of the parts from the lanes onto a belt conveyor at the base of the buffer.
To decelerate parts during filling and thereby prevent damage, the spiral tracks are fitted with speed brakes. The buffer takes a relatively small amount of floor space (33 ft 14 ft), and has been far less damaging to the valuable machined parts compared to their former storage in tote boxes.
Automatic inspection and assembly
"Rather than random sampling as in the past, we now rely upon automatic gages to perform 100-percent inspection after key finishing and assembly operations,' Wulf indicated. "For instance, the bearing bores of all completed rotor/ pulleys exiting from the last three spindle chuckers are checked to within a 0.0009 tolerance by in-line gages before being conveyed to buffer storage.
"In addition to establishing part quality, the gage measurements are relayed back to the chuckers for automatic tooling compensation.'
Completely assembled rotor/pulleys, armatures and fields are likewise 100 percent automatically inspected prior to painting or packing. Ten vital dimensions are checked on rotors, five on armatures and five on fields.
Assembly of rotor/pulleys and armatures is performed on Partsembler indexing carousels of cone-lock design. Loading and unloading is by pick-and-place units.
Room was left for a manual station between each pair of automatic work stations in case of automatic station malfunction. Each automatic station is electrically wired as if it were a stand-alone. It can be quickly disconnected and locked out so that the machine's logic assumes it is still working.
Assembly on the rotor/assembly carousel requires the insertion of a grease guard and the pressing and staking of a ball bearing. On the armature carousel, assembly involves combining the armature plate, armature body, and three springs using six rivets and two staking operations.
Painting of parts has been automated as well, and the painting procedure has been altered to ensure sufficient build and consistent coverage. Two new back-to-back lines--one for rotors, the other for armatures and fields--automatically move machined parts on chain on-end spindle conveyors through preheat tunnels (160 F), automatic airless paintspray booths and an air-dry area.
The parts are then immediately hand packed in returnable pallet cases for shipment to the automotive air-conditioner OEM customer.
"By preheating, coatings to 3 mils can be consistently obtained. Previously, the lack of preheating resulted in occasional insufficient builds and irregular distribution,' Wulf said.
Incoming quality control
The quality of incoming parts must be much higher on Warner Electric's new clutch line, compared to the quality required for the former stand-alone machines and tote-box material handling.
In process statistical quality control using X and R charts has been inaugurated throughout. Statistical capability studies have been run by Warner on all machines and processes. All recently purchased machines have been procured only after passing 4-sigma capability studies (with the 4th pertaining to temperature variables).
Purchased parts are statistically checked and suppliers are apprised of exactly what dimensions Warner Electric considers vital, what incoming quality checks will be made, and what problems former suppliers have had in making parts so that potential new suppliers will fully understand potential problems and bid appropriately.
For information from Ingersoll Engineers on their system design capabilities, circle E27.
Photo: Overhead view of the automatic rotor/pulley assembly carousel, where a grease guard and ball bearing are inserted and staked in place. The machine is fed by a spiral conveyor (left) and load/unload pic and place units.
Photo: The rotor/spun-pulley machining line, which has five three-spindle automatic-load/unload NC chuckers. Parts flow is from the rear to front in this photo, and most of the material-handling equipment visible consists of blue-steel conveyors and elevators.
Photo: Friction-face side of typical armature. The armature consists of the ground face plate, body with welded hub and internal springs assembled into a unit by staking and riveting.
Photo: Blue-steel conveyors within the rotor/spun-pulley machining line.
Photo: On the rotor/poly-V-Pulley line, automatic gaging equipment (within the expanded-metal guards) performs 100-percent inspection before the parts go to buffer storage. The gages check bores to within 0.0009, and measurements are relayed to the three-spindle chuckers for automatic compensation of tooling.
Photo: Buffer storage area for rotor/pulleys. Microprocessor controlled, the buffer features 16 independent, gravity-fed spiral lanes holding from 600 to 700 parts each.
Photo: Plan view of the new system, which measures 70 ft 288 ft. The 16-lane vertical-buffer storage conveyor is at top center.
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|Title Annotation:||Ingersoll Engineers system|
|Publication:||Tooling & Production|
|Date:||Jan 1, 1984|
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