Write down the part, not the product category
Hot bending is specified part first, machine second. Before any capacity or temperature figure is discussed, the supplier needs a drawing of the blank and the formed piece: outline dimensions, corner radii, the bend you need to hold, thickness before and after forming, and which surface must stay optical-grade. A part that enters as a flat blank and leaves as a curved cover behaves differently from one that starts curved, and that difference moves the tooling design before it moves anything else.
Attach the tolerance you will be judged on, expressed as the deviation you are willing to reject. Optical and display covers are usually inspected against a contour deviation, a surface-defect rule and a dimensional check on the finished piece, so send the inspection print or the incoming-inspection rule that applies to your part. A supplier cannot tell you whether their process holds your contour without knowing your contour limit.
Size the machine to the part size and the shift plan
The diagonal or overall footprint of your largest planned part, plus a margin for the next part you expect to run, is what determines whether a machine fits your product range at all. The page for our 3D curved glass hot bending forming machine states an applicable size of 14 inch within, so parts beyond that size belong in a different conversation. State your own maximum now rather than asking later whether the machine can stretch.
Then describe the production duty in the same terms you will be measured on: pieces per shift, number of shifts per day, whether one line runs several part numbers or only one, and whether the plan is a trial cell or continuous output against orders. The same page records a cycle time under 180 seconds per piece and 30 moulds in the normal cycle of the machine. Those two numbers, read together with your part count, are what tell you whether one cell is enough or whether the plan needs a second fixture set and a changeover rule. Ask for those figures for the machine you are being quoted, not the marketing sheet, and put them in the comparison table as the supplier's stated values.
State the quality standard in the supplier's own categories
Machine pages publish quality figures in two separate categories, and the difference between them decides what you sign for at acceptance. The record for our machine lists an equipment failure rate of 2 percent or less and a product pass rate of 80 percent or above. A failure rate describes the equipment being available; a pass rate describes your parts coming out good. A quotation that promises only one of the two leaves a hole in the acceptance test.
Write your own target next to each category before you send the enquiry: the pass rate you need on your part geometry, and the availability you need to protect your order commitments. Also send the definition your inspectors use for a reject, since a supplier can only build a test around a defect you have described. If your part is inspected by an automated optical system, say so, and ask whether the machine's process can be evaluated against that system or whether a separate inspection step has to be planned.
Declare the process controls you expect to see and to record
Hot bending is a thermal process run inside a controlled atmosphere, so the information you need from a supplier is how the process is held and how it is proved. On the published record of our machine the working mode is dual high-frequency heating with a forming temperature of 600 to 850 degrees Celsius, the heating temperature and heating time can be set and displayed on the touch screen, the thickness of the mould is detected and monitored before discharge, and circulating oxygen detection runs on four chambers filled with nitrogen gas with an oxygen controller, with cavity oxygen content stated at 50 ppm or less.
Send the controls you personally need to be able to read at the end of a run, and ask three questions in writing: who can change a recipe and who is locked out, whether every cycle leaves a record you can export, and what the machine does when a monitored value drifts out of range. A supplier who answers those three questions with named functions is giving you a traceable process; a supplier who answers with reassurance is not.
Describe the fixture plan and the changeover you expect
Moulds and fixtures are where a hot-bending project usually stalls, and the buyer's job is to describe the changeover before the machine is ordered. Say how many part numbers the cell must run in its first year, whether those parts share a fixture or need their own, how quickly the fixtures must swap, and who owns the tooling design if the drawing changes after delivery. The 30-moulds-in-normal-cycle figure on our machine page is a useful reference point for how many fixture sets a cell is expected to carry, but it belongs to that machine, so ask the supplier for the equivalent figure for the unit you are being quoted.
Add two practical items to the same paragraph of your enquiry: the lead time for a replacement or additional mould set, and the wear-monitoring rule. Mould-thickness detection is a control on our machine; ask what a candidate machine monitors, and what the written replacement criterion is. Mould wear turns a stable process into a drifting one long before anyone notices on the shop floor.
Define the trial before the quotation, not after the delivery
Send real blanks with the enquiry and ask for a sample set on your part, with the trial conditions and the results written down. A useful trial report lists the recipe that was used, the atmosphere readings during the run, the cycle time actually achieved, the pass rate on your blanks, and the measured deviation against your drawing. If a supplier cannot produce that record, the acceptance test at your plant will be argued rather than measured.
Put the acceptance condition into the purchase order in the same words you used in the enquiry: which metric is tested, on which part numbers, over how many consecutive pieces, who attends, and what happens if a figure is missed. That single paragraph turns every earlier number in this article into something enforceable.
Set the utility and site boundary in writing
The supplier needs to know what your site can supply, so state the boundary before installation is discussed: available power and its quality, the nitrogen supply and how it reaches the machine, floor space including access for maintenance, and any compressed air, cooling or extraction the cell will need. Ask the same question back in writing and have the answer reviewed by your facilities team before the order is placed.
A hot-bending cell sits inside a plant that already has rules for commissioning, safety sign-off and shift working. The integrated engineering team services page lists project plan development, task decomposition, stage node management and customer acceptance support among the project-engineering outputs, together with the factory inspection standard and acceptance data that come out of a delivery. Use that same document set as the shape of your own readiness file.
Close the comparison with one question about the team behind the machine
A specification only holds if someone answers for it after go-live. For each quotation, record who is responsible for process tuning, who owns the spare-parts position, and what happens to the recipe if a key engineer leaves. If your own organisation is short of mechanical, control, testing or manufacturing engineering at the moment you plan to install, say so in the enquiry; it changes the proposal you get, because a supplier who can staff those roles beside your team will scope the project differently from one who ships a machine and waits.
If you want the machine-side answers written down against your part, send the part drawing, your target pass rate and your shift plan to the Shenzhen PowerDe Automation Precision Equipment contact page, and we will return the applicable figures for the unit your parts would run on.
