Line Changeover and Setup Verification

A changeover replaces one product with another on the same line. The risk is not the new product, which is set up deliberately, but the remains of the old one, which are removed by assumption.

Line Clearance

Every component of the previous build has to leave the line, including partial reels, feeders that are not in use and boards from the previous lot. A partial reel left on a cart is the classic source of a mixed build.

The clearance should be signed off by a person rather than by the team collectively. Our floor control notes describe the arrangement.

Program Recall and Its Verification

The machine recalls the placement program and the printer recalls the stencil and the print parameters. Both should be verified against the work order rather than trusted to the recall.

The verification is a comparison, not a glance. Our fabrication notes list the points to confirm.

Feeder and Nozzle Setup

Feeders are prepared off line on a cart where possible, which shortens the changeover and moves the verification earlier. Each position should be checked against the setup sheet.

The nozzle set changes with the part mix. Our placement accuracy notes describe the effect of the wrong nozzle.

Stencil and Paste

The stencil belongs to one product and it should be checked against the work order, along with the paste lot. A stencil from a previous revision looks correct and prints the wrong apertures.

The paste should be within its working life. Our paste handling notes describe the routine.

First Article

The first article confirms that the setup produces the intended assembly. It is the check that catches a wrong program, a wrong feeder or a wrong stencil before the run.

It should be recorded per changeover rather than per shift. Our first pass yield notes describe the record.

Time and Its Trade

A thorough changeover takes longer than a hurried one and it prevents a run of assemblies that are uniformly wrong. The trade should be visible in the changeover time target rather than left to pressure on the line.

Our line balance notes describe the throughput context.

Verification

The verification is a signed line clearance, a program and stencil compared with the work order, a feeder position checked against the setup sheet, and a first article recorded for every changeover.

Our quality notes describe how the records are kept.

Process Control and Verification

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. Documenting the assumption is part of the design work, and a short note on the drawing prevents a question that would otherwise arrive a day later and cost a day of schedule.

The process window is set by the narrowest step in the flow, so an improvement anywhere else shows up as margin rather than as yield until that step is addressed. A short note on the drawing about handling, storage or packaging is often worth more than an extra decimal place on a tolerance.

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.

Checks Before Release

The checks that matter are the ones performed on the product rather than on a sample kept for the purpose, because a coupon that travels with the panel is the only evidence about that panel. Where a requirement can be measured, it should be measured at the point of manufacture and recorded against the board or the lot it applies to.

A parameter that is set once and never re verified drifts, and the drift is usually discovered by a defect rather than by the record. The tooling, the material and the profile form one system, and a change to any of them should be assessed against the other two before it is released.

Where the process window is narrow, the measurement resolution has to be better than the window, or the data cannot distinguish a good part from a marginal one. A record that identifies the operator, the date and the settings is worth more than a record that identifies only the result.

The acceptance criteria should be written before the work starts, so that the decision is made by the specification rather than by the person inspecting.

FAQ

Is a first article needed after every changeover? Where the product changes, yes. Where only the reel is replenished with the same part, a setup check is enough.

Can the changeover be done by the operators alone? It can, provided the clearance is signed and the setup sheet is followed rather than remembered.

What does gopcb provide at changeover? We provide a signed line clearance, a program and stencil verified against the work order, feeders prepared off line and checked against the setup sheet, a nozzle set matched to the part mix, and a first article recorded for every product change.