Workstation Design in Medical Device Manufacturing

Workstation Design in Medical Device Manufacturing Rachel Michael, CPE, CHSP Senior Consultant Ergonomics Thought Leadership Aon Risk Solutions Global Risk Consulting Casualty Risk Consulting m: +1.385.230.5838 rachel.michael@aon.com aon.com

Introduction Rachel Michael CPE, CHSP Vice President, Board of Directors BCPE ASSE Ergonomics Practice Specialty Proprietary and Confidential aspects of project Desire for improved performance and cost reduction

Current State Ergonomics Employee complaints and task self selection Turnover impacting production 3-6 months of training to get to full production Hand/wrist Injury and WC claims Process waste

Current State Ergonomics

Current State Ergonomics What design guidelines /task analysis tools are currently available? What are the limitations? What do we need for future state goals? What can we actually get?

Determination of Design Targets Based on data provided by the National Institute of Occupational Safety and Health (NIOSH), 1997 epidemiologic studies have examined physical workplace factors and their relationship to hand and wrist injuries and disorders (Carpal Tunnel Syndrome or CTS, and tendinitis).

Determination of Design Targets NIOSH states that there exists a positive association between highly repetitive work by itself and the likelihood of developing CTS and tendinitis in the hand. When risk factors are combined, for example repetition and high force, there is even stronger evidence that supports an even higher probability of developing hand and wrist injuries.

* Silverstein 8

Determination of Design Targets Determining guidelines for muscle exertion levels depending on the frequency of exertion (repetition). Reductions in muscle effort, measured in terms of percent Maximum Voluntary Contraction (% MVC), allow for increased blood flow, less centralized fatigue, and allow people to perform more work (repetitions) at a lower risk of injury.

Determination of Design Targets Research has indicated that at muscle contractions below 10% MVC blood flow is not restricted and that the physiological equilibrium of the muscle is maintained at an aerobic level. At muscle tensions of 20 30% of MVC blood flow restriction can occur, limiting the oxygen supply and the removal of waste product from the muscle.

Determination of Design Targets Contractions exceeding 30% of MVC result in a decrease in blood flow. Total blood flow occlusion occurs at approximately 80% of MVC and should only be performed on a very infrequent basis.

Determination of Design Targets Frequency Guide for Muscular Exertions Peak Muscle Efforts Occasional tasks Frequent tasks/ Static Work Highly Repetitive Tasks Infrequent work once every 4 hrs. Efforts 4/hour 1/min (28 to 420/day) Efforts 2 6/min (840 to 2,499/day) Efforts >6/min (>2,500/day) Muscular Effort Level Guideline <80% MVC <30% MVC <20% MVC <10% MVC

Determination of Design Targets Great! Now how do we go about getting to %MVC of current and future tasks?

Project Goals The goal of the study was to use objective data to identify actual muscle forces, postures and repetitions required to perform the tasks, and compare these results to ergonomics guidelines. Teams will then have comparable data for each aspect of the task to assist in making any design changes or equipment purchases.

Pipette Group 9 employees participated in the study (7 Females and 2 Males) 12 Tasks were analyze with each employee performing multiple trials within each task 3 Pipettes were used by the employees

Assembly Group Identified 8 employee volunteers. Employees were categorized as Expert (3), Intermediate (3), Beginner (2) Data captures: Right and Left hand (pinch) force, Right and Left hand EMG (pinch) muscle activity and right wrist flexion/extension, ulnar/radial deviation 5-6 tasks on two production lines were reviewed

Thoughts so far? What are your thoughts on the group? Sample size? Potential other issues?

Measurement Equipment A digital force gauge was used to measure actual mechanical forces in work tasks Surface force/pressure measurements collected Surface Electromyography (semg) was used to measure the actual muscle forces As muscles contract, microvolt level electrical signals are created within the muscle that may be measured from the surface of the body

Measurement Equipment Wired but with BlueTooth data feed

Measurement Equipment Time consuming to apply Can be viewed as invasive Consistent placement and measures important to data integrity Clean room approval Can be viewed as disruptive to process

Measurement Equipment * Reference Seniam.org

Measurement Equipment

Data Collection

Non value added left hand muscle use. Right index finger peak forces.

Data Collection Yay! We ve got data! Now What?

Data Collection Muscle were calibrated using a Maximal Voluntary Contraction method (100% MVC) Data analysis consists of comparing the task activity levels to the 100% MVC files Average and peak %MVC muscle efforts were then calculated for each task

Results and Discussion Got it! So everything is compared to 100% MVC And then we take the average And then we design to below either 10 or 20% Right??

Results and Discussion GROUP B EMG 2 Peak EMG 2 Ave EMG 3 Peak EMG 3 Ave EMG 7 Peak Task 1 79% 5% 130% 13% 79% Task 2 109% 6% 102% 14% 51% Task 3 103% 6% 119% 11% 86% Task 4 62% 6% 86% 9% 74%

Results and Discussion Sub# LT LF RT RF 1 15.92% 14.55% 13.71% 10.29% 2 23.55% 5.41% 0.33% 0.31% 3 18.46% 12.44% 23.20% 12.33% 4 4.52% 2.07% 8.20% 3.60% 5 11.15% 8.18% 30.27% 5.40% 6 28.14% 7.76% 8.78% 10.74% 7 12.55% 6.77% 8.60% 2.75% 8 17.47% 3.21% 14.55% 13.03% 9 28.30% 6.52% 23.85% 7.18% AVE 17.78% 7.43% 14.61% 7.29% Variation 8% 4% 9% 5% 30

Results and Discussion

Results and Discussion- Pipetting It was estimated that the employee s may perform on average around 3.14 repetitions per minute using a variety of pipettes The 3.14 represents the number of muscular exertions and not the number of samples processed in a shift These repetitions can vary across the actual tasks being performed and shift length

Results and Discussion- Pipetting Using the value of 3.14 reps/min the ergonomic guidelines indicate that muscle force levels should be less than 20% MVC. Upon review of the data the average % MVC value of 20% was exceed by at least one muscle site under investigation in 3 tasks Task 2 - (left and right Thenar muscle) Task 11 - (right Thenar muscle) Task 12 - (left and right Thenar muscle)

Results and Discussion- Pipetting Due to difference in subject hand strength on average only three tasks would exceed 20%. Reviewing the variation (standard deviation) did reveal that certain employees would be at risk due to the lower overall of pinch and grip strength

Results and Discussion- Pipetting Upon review of the data the variation around the average % MVC value of 20% was exceed by at least one muscle site under investigation in 8 tasks Upon review of the data the average % MVC value of 80% was exceed by at least one muscle site under investigation in 3 tasks Upon review of the data the variation around the average % MVC value of 80% was exceed by at least one muscle site under investigation in 10 tasks Now we can translate into design!

Results and Discussion- Assembly Upon review of the data the variation around the average % MVC value of 10% was exceeded in repetitive work (20% for less repetition) in many tasks. The peak force exceeded 80% for many repetitive daily tasks. Beginner group had statistically significant higher force production through hands.

Results and Discussion- Future State Task - Beginner group Design 1 Design 2 Design 1+2 Task 1 < 2% 12% MAYBE Task 2 < 2% 0% NO Task 3 0% NA NO Task 4 15% 5% YES

Results and Discussion- Future State New Hire training Evidence based task rotation Claim validation Early/Full RTW Targeted design improvement Cost reduction through equipment spec up front

Questions? Rachel Michael, CPE, CHSP Senior Consultant Ergonomics Thought Leadership Aon Risk Solutions Global Risk Consulting Casualty Risk Consulting m: +1.385.230.5838 rachel.michael@aon.com aon.com