Eyeglass frame welding
Eyeglass Frame Welding: One Joint, and the Whole Frame Pays for It
The frame is already plated. The endpiece has gone, and the joint you need is smaller than a grain of rice. The bill it writes is for the whole frame.
Micro welding on metal frames — and a straight answer about what the heat does to the rest of the frame, not just to the joint.
Most suppliers answer this with "yes, we can weld that." Every frame that came back wrong was welded by someone who said exactly that. What follows is the other half: which plated frames we will still work on, which ones we tell you to leave alone, and what the hinge has to do after the joint is made.
The day an IP, PVD, enamel or painted frame first lands on your bench, the old habit — weld it now, re-plate it after — stops working. That is usually the day this question gets asked out loud.
What breaks on a metal frame, and where the break sits
Five parts, three metals, and one of those parts is not a shape at all — it is a mechanism.
The parts that reach us are endpieces, hinges, bridges, pad arms, snapped temples.
The metal is usually one of three: titanium fronts, stainless hardware, plated brass components. A single frame can carry all three within a few centimetres of each other, which is why "what is this frame made of" so rarely has one answer.
Where the break sits decides more than how big it is. A bridge or an endpiece break sits in the front — in full view the moment the frame is on a face. A snapped temple sits behind the lens, out of anyone's line of sight. A hinge break sits on the one part of the frame that has to keep moving when the job is finished. Same size of joint, three different things at stake.
When we will weld on a plated frame, and when we say don't
Three situations where the joint is still ours to make. Four where the honest answer is no.
Still ours to make:
- The break is not in the front visible area.
- You have already accepted that the whole frame goes back for re-plating.
- The finish is ordinary plating.
We will say don't weld on the plating when:
- The break lands in the front visible area — the one place where a re-plate's colour difference has nowhere to hide.
- The frame has been re-plated several times already, so the layer is thick and its adhesion is poor.
- The finish is IP, PVD, enamel or paint. Re-plating does not put those back the way they were; it puts something else there instead.
- The lens is still cemented in and will not come out. What we need to hear about that one is further down this page.
None of the four is settled by a photograph, and none of them is settled by the frame's model number. Whether one has landed on your frame is something the frame itself says — send it in and we will tell you which of them applies.
And if the frame is already plated: price the re-plate of the whole frame into the job before the work starts, rather than finding out afterwards. Plating does not discolour locally. It discolours, and the frame goes back as a whole.
Where the joint belongs on a frame line
Six stations. The weld has one place to sit, and two of the stations do not let you back through.
Forming and component machining. Welding, at the bare-metal stage. Grinding and polishing. Plating or surface finishing. Assembly — lens cementing, hinge closing. Delivery.
Two of those are one-way. Once the frame has been through the plating tank, every joint made after it is a joint made on a finished surface. Once the lens is cemented and the hinge is closed up, the heat has places to go that nobody chose for it.
So the standard place for the weld is the bare-metal stage: after the parts exist and before anything has been put on them or into them. That is the station where a joint is only a joint.
On the frame already in your hand, this station has been passed. On the next batch, it has not — and that is the whole of the difference between the two conversations.
Up to here the question was what one joint costs the whole frame; from here it is whether the part still works once the joint is made.
A hinge is a mechanism: it still has to open and close afterwards
The first batch that comes back from the assembly bench with "these don't sit right" is not a batch of failed welds.
Work the temple. That is the check, and it happens after the bead has cooled, not while it is being made.
The criterion on a hinge is not that the joint holds. It is that the hinge still opens and closes where it belongs once the joint is finished.
A bead can be sound and the part still be scrap, because what was scrapped was the movement, not the metal.
Before any heat goes near it, there has to be a reference the part can be returned to — the mating hinge half, or a fixture that puts the two into the same relationship every time. Weld without one and you are welding to a position nobody can check afterwards.
And we do not weld a hinge that has already been closed up. The heat travels into the pin and across into the other half, and what began as one damaged half ends as two.
That is one hinge on one frame. What you do with the rest of them is a different decision.
Weld one frame first, then move on the batch
A brand drops a new spec: same joint, same frame, quantity and date fixed in the same sentence.
That is the moment the question changes. It is no longer "can this joint be made" but "can it be made the same way, this many times, starting now."
The order that answers it: weld one. Work its hinge, sit it in the assembly it belongs to, look at it once it is cold. Then set the rest going.
Run the batch first and check at the end, and the rework is the batch. That is the difference between losing an hour and losing the order — and it is a decision about how you start, not about how fast anyone welds.
The first piece only settles anything if there is something to judge it against, and that part does not come off the drawing — put one real frame through it before the batch moves.
Touch one point, and it is never that point that settles up.
One pairing we talk you out of, one we have to test before we answer
Same-metal joints are the straightforward half — titanium to titanium, stainless to stainless, one precious metal to the same precious metal. Two other cases need naming out loud.
We talk you out of it — a titanium front to stainless hinge hardware.
The bead here can come out excellent: even, bright, exactly where it was put. Loaded, it still cracks through at the interface. It does not fail on our bench, which is the problem — it fails later, on someone's face, and by then the frame has been through your assembly and your customer's hands.
So the answer we give is a different joint, not a better weld: a mechanical connection, or a transition layer between the two metals. We would rather hand you that route than a joint that looks right — it sits with the rest of the pairings we turn down, each one with the route we send it down instead.
We have to test first — zinc-bearing alloys and coatings, which on frames means plated brass and zinc-plated hardware.
Zinc leaves long before the base metal melts, and it leaves violently. What you get is porosity, spatter, a bead that is loose through the middle. Often the fix is not a parameter at all but the shape of the joint — opening it so the vapour has a way out.
So this one gets a test weld, and the parameters come from what the test does. Nobody promises it right the first time.
Three things to tell us before a frame goes in the post
You know all three. We know none of them until you say so, and each one changes whether the job exists.
Is the lens still in the frame.
If it is, does it come out.
Which finish the frame carries — ordinary plating, or IP, PVD, enamel, paint.
We do not weld on a frame with the lens still cemented in. The cement gives way first, and it gives way quietly — the metal is nowhere near bothered by the time the lens has let go.
If the lens will not come out, the frame does not get a yes or a no from a description. It gets looked at on its own terms, one piece at a time, and what you get back from us is what we found — not what we hoped.
Which machine eyeglass frame welding lands on
Two kinds of work sit on the same bench, and they point at two different machines. Neither of them is "the one for eyewear."
Endpieces, bridges, pad arms. Thin, heat-sensitive, with plating and cemented lenses sitting close by — and in a frame shop they arrive as small repeat batches built to a brand's spec. Thin-walled or heat-sensitive parts, low heat input and line cadence → QCW. The half of that line doing the work here is line cadence: the same joint, made again and again to the same spec, at the pace the batch has to move.
Hinges and the small hardware around them. Here the spot has to land exactly where it was aimed, on a part that will keep moving afterwards. Fine tack welding, small spot → EU Style.
Which of the two your bench actually sits on is settled by the joints you actually make, not by a specification read side by side. Send a frame in and let the trial weld answer it.
One frame, or that batch
Two different questions. They do not take the same road out.
Still deciding about this one frame. Whether it can be worked on the plating, whether the hinge comes back moving, whether the lens has to come out first. None of those is settled by a description, so it goes the short way: one frame in the post, and an answer that came from the frame itself.
Free weld sample evaluationAlready past that, and pricing a batch. You know which machine, you know the joint, and what is open is the number on the page: request a quote. If it is neither a quote nor a trial weld, say what it is and we will answer that instead.