The most cost-effective time to make high-impact improvements to equipment or workstations is before they have been installed on a plant floor; after that, all modifications guarantee additional expense. Unfortunately, not all engineers know what to look for when evaluating a drawing or a pre-built station for MSD risk factors. The first visuals that engineers will be able to evaluate are generally 3-D engineering drawings of the parts and/or production equipment. Since the parts themselves and the production equipment or workstation affect the final process in different ways, they must be evaluated using different methods.
Part design drawings
Engineers should focus on how easy or difficult it will be to put all of the smaller pieces together, as well as how and where the operator will be holding the parts during this process. Engineers should be asking:
- How much will this part weigh?
- Are the tolerances between parts reasonable for manual insertion?
- Will the operator have to rotate the part during assembly?
- How many total parts are being assembled to make the final product from this line?
- How many different fasteners and/or different torque values will be used during assembly?
Equipment and workstation drawings
Engineers should look at how the operator will be interfacing with the workstation. They should ask:
- What is the horizontal reach to load the part?
- Where are operators retrieving new parts from?
- Do operators interact regularly with the display controls?
- Is there anything hanging or overhead that the operator will have to duck to avoid?
- What is the hand working height (including part heights and tool height)?
- What are the visual sight lines to the tasks performed?
After the designs have advanced past this stage, the focus shifts to the production equipment and tools required to build physical parts. The responsibility for evaluating the ergonomics of the built equipment lies with the industrial and manufacturing engineers. When these individuals visit a supplier to review their equipment before officially approving it for delivery to a plant, there are multiple factors for them to review, even without ergonomics. Therefore, it is best if they have a standard checklist that reminds them which risk factors to look for by measuring physical dimensions, such as exact hand height and the horizontal reach when loading/unloading parts. This checklist should include a review of material flow through the station, focusing on how fresh parts will be picked and where the finished assembly will be placed. In order to properly evaluate all this information for the level of MSD risk, it is critical the reviewer has the following process information:
- Parts produced per day
- Cycle time of each station
- Number of operators at each station
- Population that will operate the production equipment
A checklist that combines prompts for each stage of the design and allows the engineers to track the review process throughout the project’s lifecycle will improve the value of each design review. It will guide engineers to ask the critical questions at the critical times to make low-cost and high-quality changes to designs.