Optimization of ATV Erector SetThomas MalloyApril BouquardAbdulrahman Mohammed NuhuliLeonard Arambam
Agenda
● Time Standards● Line Balancing● Workstation Analysis● Ergonomics● Part Presentation● Iterations● 5S implementation● Conclusion
Time Study
Part 1:
● Members worked alone on constructing entire ATV.● Identified steps to be timed (Battery, 1-24)● Timed each step in seconds
Part 2:
● Users’ times were averaged together to identify standard assembly times.
Phase Time (hrs)
Average 2.53
Final 1.16
Line Balancing
Goal: We want all workers to have the same amount of time spent working.
● Precedence constraints did not allow for optimal usage of Largest Candidate Rule○ Grouped steps were very restrictive
● Divided steps into 8 blocks to be divided between 4 workers.○ 4 Long blocks and 4 short blocks
Worker # Time (sec)
1 2207
2 1973
3 2217
4 2710
Line Balancing (cont.)
● We reallocated steps from longer times to shorter times, but as the assembly progressed we could not have all workers actively working on the same product.
● Idle times between blocks allowed for flexibility.○ Workers could help others when they lagged behind
Workstation Analysis
● Due to kitting and task analysis, workers needed to be close together.
● Ordered 360 Degree Rotational Vices for each workstation.
● Separated black screws and ¼” nuts into separate containers.
● Kept tools in order● Materials lay flat on the workstation (nothing
above the head)● No foreign objects permitted
Workstation Analysis (cont.)
● Seated work aided in fine assembly and allowed for necessary communication
● All materials were within 24 inches of the worker
● Most used materials were within 14 inches● Adjustable chairs with wheels provide
ergonomic benefits for workers of all heights as well as ability to move laterally along workstation
● Elevated tables for larger workers
Workstation Design Benefits
● Promotes a social atmosphere.● Task order automatically designates idle times for workers● Allows for quick passing of assembly● Provides help from idle workers
Tooling
● Magnetized Allen Wrench● Standard C-Frame Wrench (stock with set)● 360 Degree Rotational Vice● Spring Clips
● Power tools were bulky and too powerful○ Stripped screws/nuts○ Caused hand cramps/aches
● Hand tools allowed for precision and accuracy
Part Presentation
● Kitted parts rather than binning○ Reduced time spent searching for parts.○ Logical order to the steps
● All parts for worker job were within reach● Kits had picture instructions as well as
what to do when a set of steps was finished.
5S Implementation
● Sort: Separate the unnecessary from the necessary parts ● Shine: Place for every part - labelling ● Set to order: Clean the workplace before manufacturing start of shift● Standardize: SOPs ● Sustain : implement and execute
Ergonomic Evaluation Methods
● ACGIH TLV for Hand Activity● Lighting Conditions ● Posture and repetitive work ● Mechanical Safety● Job rotation.
ACGIH TLV Evaluation Purpose: To asses the risk of hand injury in performing physically continuous demanding jobs
Methods: Conducting ACGIH TLV for Hand Activity by accurately observing the steps through videotaping
Results: Our results indicated that most of the work done by our right hand needed some modification.
Implemented Improvements
● Ordered two 360 degree rotational vices to reduce TLV scores● Magnetic Allen wrenches reduce overall movement during tightening the
screws and decreased the number of lost screws due to dropping● Holding the assembly in with the vice reduced the strain on the dominant
hand while increasing nondominant hand usage
Lighting Conditions
OSHA Recommended:
● Illumination needed: >1500-2000 lux(lumen/m^2)● Installation of overhead florescent lamp in the workstation with > 40 watt● Incandescent lamp in the room with > 20 watt
Posture and Repetitive Work
● Total work per day: 8 hours with one hour lunch● System capability: 16 ATVs ● Height adjustable chairs● Elevated tables for comfortable leg room
Job Rotation
● Eliminate monotonous jobs and potentially harmful posture● Cross functional training leads to a fully flexible workforce ● Isolate worker strengths● Increase satisfaction and decrease muscle weakening rate ● Motivate employees to deal with new challenges
Iteration #1: Assembly Line/Binning
● Assembly line with binning at each station● No change in step order● Precedence constraints were severe● No drastic change in time from single worker method
Iteration #2: Binning/Current Workstation Layout
● Allowed workers to work simultaneously● Confusion during part selection● Increased work time/lack of idle time● Implemented magnetic c-wrenches and allen wrenches
Iteration #3: Kitting/Current Workstation Layout
● Easy part selection● Low precedence constraint effect● Workers had idle time to reorganize workstations● Provided quickest assembly time● Removed magnetized c-wrench tool after it was found to be ineffective
Quality Assurance
● Worker checklist to ensure all steps are performed
● Signoff sheet to link worker with steps performed as well as determine routings
● Standard Operating Procedures were developed to standardize the way steps were performed.
Workstation Recommendations
● Drawers or overhead hangers for tool storage● Lightweight automated tools calibrated to output a set pressure/rotation● Flow racks to allow for kits to roll towards and away from worker● Cross training workers to better utilize skills
Idle Time
● Work on wheel assemblies or other small tasks● Organize workstations● Restock materials● Help other workers● Perform quality checks● Start on a new kit
Conclusions
● Average Takt Time of 29 min● Layout provided a “team” mentality● Kitting reduced time spent searching for parts● Magnetized tooling aided in assembly process● 360 Degree Rotational vice freed non-dominant hand● Cross training workers allows for flexibility and cost efficiency
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