Department of Industrial and Engineering Technology College of Science and Technology Morehead State University IET 317 Group 5 Project Group Members: James Forrest, Lowell Outland, Evan Scott, Donald Snyder, Matt Wells Steel Wheel Assembly Work Cell

Central Motor Wheel of America (CMWA)  CMWA was established in  Location: Paris, Kentucky  Employs approximately 500 people.

CMWA Products  OEM supplier of Steel and Aluminum Wheels.  Steel Wheel Customers: Toyota, Honda, and Hyundai  Aluminum Wheel Customers: Toyota and Lexus.

Rationale for selecting the Steel Wheel Assembly Station  The rationale for our chosen process is simple  A work cell is a collection of equipment required to make a single complex part  The part being produced is the steel wheel  The Steel Wheel Assembly Station itself has many parts. (Including: the operators, robotic loaders, punch press, date stamp device, welders, grinders and inspection)  Multiple factors can lead to the occurrence of waste

Rationale cont.  If diligent lean techniques aren’t practiced in this work environment, the efficiency of the work cell could easily deteriorate, wasting valuable company time and money  In our efforts to make improvements we analyzed the processes of the Steel Wheel Assembly Station  Identified areas that can be improved  Made suggestions on how to improve them to make it a more lean and efficient process

Description of Steel Wheel Assembly Station The cell is used to assemble two main components of a steel wheel. The two components are the center disk (wheel center) and the Rim (outer part of the wheel). These parts are placed near an operator at the beginning of the assembly line. At the beginning of the wheel assembly machine there is one operator. This individual is responsible for loading the center disk onto the conveyor belt and loading the rim into a small punch press. This punch press is responsible for punching out the valve stem hole. The punch press side of the line will be discussed first. The operator grabs a rim (6sec.) and places it onto the punch press (3sec.), he then activates the press which locks the rim into place and almost simultaneously punches the hole for the valve stem (2 sec.). Once this operation is finished a mechanical arm pulls the rim onto a conveyor belt directly in front of the punch press (Note: as the mechanical arm is pulling the rim on to the conveyor the operator is loading a center disk onto the other line). The rim continues down the conveyor to the stamp station which automatically positions and clamps the rim (2sec.). This station stamps a date (2sec.) onto the rim so that when the two parts are welded together the company has a record for quality assurance purposes. On the wheel center side of the line, the operator has to just load the part so that it travels down and stops near the two weld fixtures. Please note that the operator is responsible for keeping both conveyor lines full. At this point two additional operators are simultaneously grabbing a rim or a center disk and loading it into a weld jig. They then retrieve the opposing part and place it into the jig (20 sec per operator). The operators then activate the hydraulic clamps (2sec. per operator) to hold the parts together during welding. The welding process automatically starts as soon as the parts are clamped together. The welding robot is equipped with four MIG (Metal Inert Gas) guns that feed the wire continuously to create a seamless weld. The pallet that the parts are clamped to only has to rotate approximately 92 degrees to create the finished weld. The welding process takes about (30sec per assembly.). Once the parts have been full welded the newly formed wheels are removed by mechanical arms and placed (8sec.) onto another conveyor belt. The wheels then travel to an automated grinder that grinds/polishes the welded seam (15sec per wheel). The wheels then travel on to an inspection station where they are checked for visual and mechanical defects by a fourth individual. This takes approximately 15-25sec per wheel. There are time variances due to anomalies in the weld or grind finish that occurs from time to time and also indicated run out noticed on the inspection gage. The total amount of allowed run out is 0.3mm. This is the end of the journey for the newly minted wheel. The wheels next stop will be the powder coat/paint booth which is another work cell. Please note that the work cell is full of parts at all times so conveyor length is not a factor. As it was explained to our group the work cell is not timed linearly due to the fact that mechanical breakdowns are anticipated especially where the welders and grinders are concerned. Also, the nozzles must be cleaned and guides replaced after X-amount of wheels are welded.

Work Cell Layout Steel Wheel Assembly Machine Wheel Rim Rack Wheel Centers Rack Punch Press (Valve Stem Hole) Date Produced Stamped on Rim Wheel Welder 1 Wheel Welder 2 Finish Grinder/ Polisher Inspection Gage Manual Load/1 Person Manual Load/1 person Manual offload/ 1 person Note: Four Person Work Cell Manual Load/1 Person

Time Study Analysis StepTime (in seconds) Acquiring materials6 Loading Punch Press3 Small Punch Press (valve stem hole punch)2 Stamp Station Load2 Date Stamp (for quality assurance)2 Loading Weld Jig20 Activate Hydraulic Clamp2 (per operator) Welding Process**Approx. 30 (per operator) Remove wheels8 Grind weld seam15 Visual inspection*15-25 Total cycle time per assembly * Time anomalies due to defects found on assembly during inspection. **Times inaccurate due to required maintenance i.e. cleaning nozzle and replacing guards

Suggested Improvements  Improve /Eliminate Finish Grinder Electric motors breaks down frequently Change to more reliable air motors  Rotate conveyor belt 180 degrees Will help make the process more linear(Refer to layout)  Move wok cell closer to punch press Use conveyor between punch press and work cell Help speed up production  Add robot to place parts onto conveyor at beginning of work cell Eliminates need for manpower at this position Helps speed up production  Consider adding a third welder(identified choke point) Move worker from first station to third welder Helps to alleviate choke point  Move closer to paint booth Reduces travel time to paint  Condense entire wheel making operation Help speed up production cost prohibitive

Group Recommendations:  Recommend changing electric motors to pneumatic motors for more reliability  Recommend moving work cell closer to paint booth to reduce part travel time after assembly  Recommend adding a third welding machine to eliminate bottleneck in production  Recommend rotating welding machines 180 degrees to create a more linier product flow as shown by recommended layout

Recommended /Revised Work Cell Layout Wheel Assembly Machine Wheel Rim Rack Wheel Centers Rack Punch Press (Valve Stem Hole) Date Produced Stamped on Rim Wheel Welder 1 Wheel Welder 2 Finish Grinder/ Polisher Inspection Gage Manual Load 1st Person Manual Load/1 person Manual offload/ 1 person Note: Four Person Work Cell Manual Load 2 nd Person

Conclusion  Using Time and Motion Studies are very useful  The assembly cell can be improved  The entire wheel production operation should be reexamined  Room for cycle time improvements