Assembly Ergonomics and Workstation Design
A workstation determines how well an operator can see, reach and handle the product, and those three factors decide both the defect rate and the rate at which the person tires. Ergonomics is therefore a quality subject rather than a comfort subject.
The design is a set of dimensions and positions rather than a piece of furniture, and it can be reviewed against a checklist before the line is built.
Bench Height and Working Posture
The working surface should be at a height that allows the elbows to be close to the body and the wrists to stay neutral for the task. A bench that is too low forces the shoulders up, and one that is too high forces the elbows out.
Where the tasks differ between stations, the height should follow the task rather than the room. An adjustable bench or a platform is the practical solution.
Reach and Component Placement
Everything the operator needs should be within a comfortable reach, which means the material and the tools should be arranged around the work rather than behind it. Reaching repeatedly is a source of both fatigue and error.
The arrangement should follow the sequence of the task, so that the material arrives where it is used. This is the same principle that applies to line balance, described for throughput planning.
Lighting at the Station
The lighting should be bright enough for the feature being judged and free of glare and of reflections from the board. A shadow that moves with the operator’s hand makes a judgement dependent on posture.
Where a microscope or a camera is used, the ambient light should not compete with the display. The inspection setup requirements are described for inspection lighting.
Tools and Fixtures
Tools should be placed where they are used, and a tool that must be picked up and put down repeatedly should be supported by a holder. A soldering iron that has to be reached for is a reason for a shortened dwell.
Fixtures that hold the board free both hands and remove a reason for improvisation, which is where defects are created.
Seating and Standing
Whether the task is performed seated or standing should be decided from the duration and the force required, and the support should match. A task performed standing requires an anti fatigue mat and a footrest position.
Where the task alternates, the workstation should allow both, which usually means an adjustable seat and enough clearance.
Repetition and Rotation
A task that repeats every few seconds with the same motion is the one that causes injury, and rotation between tasks is the practical control. Rotation also reduces the attention loss that comes from monotony.
The rotation should be planned as part of the line design rather than arranged informally when someone reports discomfort.
Environment
Temperature, draughts, noise and the smell of flux all affect the operator’s ability to work consistently. An extraction system that removes the flux vapour improves the result and the working conditions at the same time.
Noise matters most where a verbal check is part of the process, since a station that cannot be heard will have its checks skipped.
Error Proofing at the Station
The station can be designed to prevent a mistake: a fixture that only accepts the board one way, a material holder that presents the correct part, or a visual aid showing the orientation. Each removes a decision from the operator.
These measures are cheaper than the inspection that would otherwise be needed, and they are described with the same logic as the visual aids used at the station.
Review
The workstation should be reviewed when the product changes and when an operator reports a difficulty, since both indicate that the arrangement no longer matches the task. A review with the operator present is the most productive version.
The conclusions should be recorded so that the next product benefits from them, rather than being rediscovered at each launch.
Additional Considerations for This Build
Practical attention to workstation design pays for itself here, because it decides whether the finished board behaves as the drawing intended. Where the requirement is not stated on the fabrication drawing or in the assembly notes, the shop has to assume a default, and that default is rarely the value the design was simulated with. Stating workstation design explicitly, together with the tolerance that applies, removes the assumption and keeps the result predictable from batch to batch.
Process Control and Verification
On a design of this kind, reach is the item that decides how the rest of the board is arranged. Where a value sits close to a process limit, the drawing should say so, since the shop can then open the process window rather than working to a nominal figure that carries no tolerance. A stack-up that is drawn rather than described removes most of the ambiguity from a quotation, and it lets the fabricator price the board against the dielectric and copper weights that will actually be used.
Where the requirement is not written down, the shop supplies its own default, and the default is chosen for the process rather than for the design. The measurements that matter are the repeatable ones: conductor width and spacing, annular ring, finished hole size, plating thickness and surface finish are all verifiable on a coupon that travels with the panel.
Running a first article through the same checks as the production panel confirms that the two agree, and that comparison is the cheapest form of process control available at prototype stage. Keeping a sample from the panel turns a dispute into a measurement, because the same coupon can be re-examined by both parties without rebuilding the batch.
Reviewing the design before the data is released is cheaper than correcting it after the panel is in the tank, because every step downstream inherits the decision made at the front end.
Process Control and Verification
On a design of this kind, reach is the item that decides how the rest of the board is arranged. Where a value sits close to a process limit, the drawing should say so, since the shop can then open the process window rather than working to a nominal figure that carries no tolerance. A stack-up that is drawn rather than described removes most of the ambiguity from a quotation, and it lets the fabricator price the board against the dielectric and copper weights that will actually be used.
Where the requirement is not written down, the shop supplies its own default, and the default is chosen for the process rather than for the design.
A first article check confirms that the process and the drawing agree on the points listed above, and that the coupon data supports the values used in the design.
Where a measurement falls outside the expected window, the sample is retained so that the cause can be established before the balance of the batch is released.
A first article check confirms that the process and the drawing agree on the points listed above, and that the coupon data supports the values used in the design.
Where a measurement falls outside the expected window, the sample is retained so that the cause can be established before the balance of the batch is released.
FAQ
Is ergonomics only about comfort? No. A station that is difficult to work at produces more errors and more variability, both of which are quality costs.
Should the bench be adjustable? Where several people use it or the task changes, an adjustable height is the simplest way to keep the posture correct.
How is the lighting specified? By the illumination at the work surface and by the absence of glare, with reference to the feature being judged.
What is the most valuable single change? Removing the need to reach, by placing the material and the tools within the working area in task order.
