Hot-bending quotes for curved glass rarely fail because one supplier is careless. They fail because three suppliers answered three different machines. If one vendor quotes a furnace and another quotes a forming station, the price gap looks like commercial generosity when it is really a scope gap. A well built RFQ removes that noise before the first reply arrives.
The questions below follow the order in which decisions actually get made on a 3D curved glass hot bending forming machine: part first, then machine behaviour, then process control, then trial, then handover.
The drawing package and its tolerances
Send the part in the form a process engineer can act on: a 3D model plus a 2D drawing that calls out the bend contour, the deviation allowed from the nominal surface, the optical zone, and where tool marks are and are not acceptable. A bare model with no tolerance statement invites three different quality levels at three different prices.
Ask every bidder to return a tolerance stack in writing, showing which deviation they attribute to the glass, to the mould, and to the machine itself. A supplier unwilling to separate those three is not yet estimating the same job as the others.
Machine capability versus process outcome
Separate what the machine can do from what the process will deliver, and require both to be stated. Published capability for this class of equipment is normally expressed as cycle time, the largest size the tooling accepts, machine failure rate, and product pass rate. One reference build lists a cycle under 180 seconds per piece and an applicable size within 14 inches.
Then state the target as your own number and ask the supplier to confirm or challenge it: pass rate on your glass, on your mould, on your cycle. A pass rate quoted as a machine figure means little until someone writes down which glass, which mould, and which cycle produced it. Ask for the forming window as a range as well, since reference values for this equipment sit between 600 and 850 degrees Celsius, and that range is where mould design and hold time interact.
Process control you can inspect during the build
Ask which parameters the machine controls, which ones it records, and what an auditor can read out after the fact. On a reference machine, heating temperature and heating time are set and displayed on a touch screen, mould thickness is checked before discharge, and the nitrogen chambers carry circulating oxygen detection feeding a controller. The published oxygen ceiling for that build is 50 ppm or less.
Two questions settle most of this. Can the machine stop a cycle when a monitored value goes out of range, or does it finish and flag it later? And can it export the parameter record for a given batch? Control that cannot be inspected after the run is a claim you carry on trust.
Moulds, consumables and trial scope
Fix the mould boundary in the document. Who designs the mould, who manufactures it, how many cavities or sets the quoted cycle assumes, and which parts are wear items with a replacement cost. A reference machine runs 30 moulds in a normal cycle, which is one reason cavity count and consumable life change the delivered cost per piece even when the machine price is identical.
Write the trial into the RFQ rather than into later correspondence: how many samples, which inspection method, who measures, and which parameter set is recorded as the trial result. Where trial parts are not the end use, say so plainly. Suppliers price risk, and an undeclared trial scope is one way risk gets priced without being discussed.
Utilities, footprint and acceptance
Ask for the utility list and the floor space as deliverables, not as an appendix after order: power quality and load, the gas supply the chambers need, space for loading and unloading, and any environment the process control depends on. Then attach the acceptance protocol to the order: the run length, the pass rate to be reached, and the parameter record to be produced.
Ask which figures the supplier can demonstrate on the delivered machine and which were measured on a reference build. That one question separates a specification from a hope, and it is settled by witnessing the same run you will be held to.
Comparing the replies on one page
Publish the answer template with the enquiry and require it back unchanged: same units, same cycle definition, same sample count, same scope of supply, same exclusions. Then read the quotes side by side on those rows instead of on the headline price, and note where each bidder names its own glass and mould assumptions.
If the answers do not fit the template, the gap is scope, and a second round of written questions costs less than a change order after commissioning. When the machine arrives with mould design, process tuning and handover inside one contract, ask the integrated engineering team services side to price those steps as line items so the comparison stays valid after award.
What the next round should answer
A complete RFQ for curved-glass hot bending states the part and its tolerances, splits machine capability from process outcome, names the parameters that can be inspected during the build, fixes the mould and trial boundary, and closes with a witnessed acceptance run. Ask each bidder to restate every figure they quote with its measurement condition; where a number cannot be demonstrated on the delivered machine, leave it out of the business case.
Send those questions to Shenzhen PowerDe Automation Precision Equipment and the replies come back in the same order, so the second round is a comparison of scope rather than a negotiation over price.
