A Request For Quote is a document that lets job shops know what you are looking to have made and to send you quotes for making it. A better RFQ gets you better parts and lower prices. Here’s some tips.
Specify tolerances… Do you mean 1″ or 1″ +/-.001″?
Tolerances and surface finish are HUGE issues and must be specified well or you won’t get the price or part you want. No really, HUGE. If you can’t be specific with numbers, give a guideline (“45 degree chamfer .1 in long, polished finish” vs “just hit the end on a belt sander”)
A rough guide to tolerances:
- +/- .030″ is noticeable by eye with a ruler, and is easy to get done.
- +/- .010″ is noticeable with a ruler if you look real close, and is common with laser and waterjet machines.
- +/- .005″ to .001″ is fairly easy to hit with most lathe and mill operations. You can measure this with dial calipers.
- +/- .0005″ is about as close as can get without paying a kings ransom. Mostly you only need this if you need very specific close fits with other parts. You need a digital micrometer to measure this.
If a tolerance is super critical, you may need to specify exactly how to measure it.
Don’t be cagey about money…
Be up front with what you are willing to pay. Just get multiple quotes (and let the suppliers know that you are doing so) to get a good price. You won’t waste the quoter’s time, and they can give you a clue if there is a cheaper way to go or if relaxing tolerances will bring the price down to your ballpark.
Know what you are buying, how to design for a process, and where to shop…
Educate yourself about different processes. Waterjet and laser cutting has really opened up the possibilities for 2D designs. If you design your turned parts to work with a bar-feeder, they will be much cheaper. If you eliminate interior holes on wire EDM parts, you decrease cost and increase accuracy.
Make sure you know all the details for international orders…
Don’t get burned with shipping, tariffs and brokerage fees. If you will be accepting international orders make sure you know what you are getting into. Here’s the language I use: “If you are supplying from outside the continental USA you MUST include all shipping, taxes, tariffs, brokerage, customs, etc charges IN your quote. No exceptions will be made.”
A dimensioned drawing is worth 1000 words…
Do good drawings. You need to indicate at least the major dimensions to make sure you are clear with the units. Your company name, copyright notice, and a revision number would be helpful as well.
Checklist of things you need in your RFQ
- Your company name.
- Contact information. Phone number and e-mail at least.
- Part title.
- Material to be used. List a material number or a general specification. For steel hardness should also be specified.
- Who is supplying the material? I prefer to have the job shop provide the material. They tend to have better supplier contacts.
- Preferred manufacturing method. This helps reduce quality related surprises.
- Quantities to quote. Always list two or three quantities. You might be surprised how cheaply you can get more parts.
- A drawing. DXF is best for 2D, IGES or STL is good for 3D. Mark at least the major dimensions and units used.
- Tolerances. In particular, specify which tolerances you care about and those you don’t.
- Surface finish. Mirror, brushed, ground, mill, or chewed by a rhino? Also, what about special coatings like anodizing or black oxide?
- Edge finish. How clean do the edges need to be? Do they need to be deburred?
- Cleanliness. Do the parts need to be washed? Steel can be filthy.
- Target price. What you are willing to pay, and what do you hope to pay?
- RFQ award date. How long do suppliers have to get you a number?
- Delivery time line. Do you need it in 2 days, or 2 months?
- Quality control. List what dimensions and features you will check on the delivered parts. This should correlate with the tolerances you listed.
Some places to post your RFQs are MFGQuote.com, RFQWork.com, and CNCZone.com.