Attaching clips: Analysis of force pattern and applying the TLV® to recommend a standard time
- In this exercise you will estimate the standard time for one cycle of attaching paper clips to cards.
- Standard time will be based on the method described below and shown in the video
- First determine the normal time by conducting a time study or using predetermined time data such as MTM or MODAPTS
- Determine the average force during the period of work and the duty cycle.
- Next determine if and how much recovery time will be require to adhere to the recommendations of the ACGIH TLV®
- Finally explore alternative ways to reduce the force requirements and required recovery time.
Job description:
- Standing or sitting workstation (Specify range based on elbow height minus 0.1m).
- Standing workstation (could be sitting): adjusted to elbow height minus 0.1m (see Fig 1)
- Binder clips
- 3x5 card bundle
- Containers 8"x4"x3"
- RH get clip
- LH get cards
- Join clip to cards
- Aside cards with clip
 (a) |
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Steps for completing exercise
- Familiarize yourself with the job & collect necessary information for your analysis.
- Estimate absolute and relative force requirements
- Use time study or predetermined time system to determine time and force for each job step.
- Job steps or actions are based on basic motions, such as reach, grasp, move, position, hold, rest, etc.
- Job steps may be grouped based on common attributes such as force.
- Your analysis should be based on a "qualified and trained worker, normal conditions, and a normal work pace.
- Calculate: total cycle time, work time, rest time, duty cycle and time-weighted average work force.
- Use the ACGIH TLV® to determine if the observed %MVC and duty cycle are within recommended limits.
- Calculate additional recovery time if needed.
- Calculate a work standard for this job under this conditions that recognizes the recommended fatigue limits.
- Explore ways that you can reduce the force requirements as an alternative to providing more rest time.
Use "Video Analysis App
- Download video
- Open app
- Open video with app
- Record time force for each step or group of steps
- Record force estimates for each step
- Sample:
- Download:download sample results
- Open the downloaded video
- Open the downloaded sample results -- they will appear in the results table.
- Clicking on a table will move the video to the corresponding time.
- Notice that the elements are grouped based on finger force. You can increase or decrease detail as desired.
Determine force required to open clips
|
|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
|---|---|---|---|---|---|---|---|
| 3900 | 4300 | 4100 | 3800 | 3600 | 3600 | 4600 | 4200 |
- For the purpose of this exercise, assume an average clip force = 4,000 gm or 4Kg.
- Note: the force can vary greatly from one clip to another.
- How would this variability affect your management of fatigue and "standard time" recommendation?
Determine Palmar Pinch Strength and %MVC
Palmar Pinch Strength (pounds) based on a survey of 310 male and 328 females, ages 20-94, from suburban and rural seven-county Milwaukee area, and broad range of socioeconomic and occupational backgrounds.
Adapted from: Mathiowetz V, et al. 1985. Grip and pinch strength: normative data for adults. Arch Phys Med Rehabil, 66(2), 69-74.
Assume:Male strength: 12Kg; Female strength: 8Kg
| Female | Male | |||
|---|---|---|---|---|
| Req Force | Strength | %MVC | Strength | %MVC | 4 | 8 | 50% | 12 | 33% |
Determining work height:
- using: Body links & reach limits calculator
- We get:
Fig 3: Stick figures based on 5%tile female stature and 95%tile male statures and average proportions.
Summarize results (save with screenshot)
| Tcycle = | |
| Twork = | |
| Trest = | |
| Duty Cycle = | |
| %MVCwork = | |
| Max recommended DC = | |
| Additional recovery Time = | |
| Recommended work standard = | |
| Minimum work surface height: = | |
| Maximum work surface height: = |