How to quote a custom rubber gasket or seal from a drawing or a worn sample

A photo arrives on WhatsApp: a cracked black ring on a workbench, a thumb for scale, and "need 4 urgent, rate?". Before you price anything, ask five things. What does it seal, at what temperature, under what pressure and movement? What size is the groove or flange, and how many are needed now and in a year? The first three decide the compound and its hardness. The last two decide whether you cut, mould or extrude, and whether a tool is needed at all. A rubber gasket quotation built on those answers is one you can stand behind.

Why the worn part is the worst guide to size

Rubber in service changes shape. In oil it swells. In heat it hardens and shrinks. Under compression it takes a set and stays flat. Measure a worn O-ring or a door gasket and you will make a new one that is wrong by exactly the damage.

So ask for the groove, the flange face, the shaft or the bore. A fitter with a vernier can give you those, or can send a photo of the empty groove beside a steel rule. If the machine is down and nobody can measure, work from the worn part and write on the quote that the size was taken from a used sample.

The material is the second trap. A black ring could be nitrile, EPDM, neoprene or a fluoro-rubber, and each fails in its own way. Do not quote "same as original". Quote a named compound for the conditions the buyer states.

A drawing solves the size and little else. It may name a material chosen for a different machine, or none at all, so the first three questions still apply.

The five questions, ready to send

Save this as a quick reply on the phone that receives most of your enquiries:

Thank you for the photo. Five answers and I can send a firm rate:

1. What does it seal? Water / oil (which one?) / steam / air /
   a chemical (please name it) / food or drinking water
2. Temperature at the seal, lowest and highest.
   Is the machine steam-cleaned or washed down?
3. Pressure, and does the seal move?
   Still (flange, cover, door) or moving (shaft, rod, piston)
4. Size of the groove or flange it sits in, or the shaft and bore, in mm.
   A photo of the empty groove beside a steel rule also works.
5. How many now, and how many in a year?

The answers also sort the enquiry. A maintenance head who needs four for a breakdown and an OEM that needs twenty thousand a year are different jobs, and they should not wait in the same queue. Sorting them before anyone spends time costing is lead qualification.

How the answers decide the method

Questions four and five choose the method, and the method decides whether a tool appears on the quote.

• Only a handful of flat gaskets: cut by hand, by die or by water jet from sheet. No tool, a price per piece.
• Flat gaskets in steady numbers: a cutting die, which is a small one-time cost.
• Standard-size O-rings: from stock, with no tool at all.
• Door and hatch profiles sold by the metre: extruded and joined, with a profile die.
• Moulded shapes such as a lip seal or a stepped ring, in hundreds or more: a compression or transfer mould, its cost shown on its own line.
• Seals on a moving rod under high pressure: these call for polyurethane or fabric-reinforced designs, so refer them if you do not make them.

When a mould is needed, how to present its cost is the subject of our post on tooling cost in a rubber moulding quote.

What the quote should state

Name the compound, its hardness in Shore A, and the conditions you chose it for. State the size basis, either "made to groove dimensions supplied" or "made to a used sample, fit not confirmed". Give the method, any one-time die or mould cost on its own line, and the piece price at today's quantity and at the yearly quantity.

If there are two needs, give two lead times: the urgent lot and regular supply. Say what you have not done, such as fitting or testing in the buyer's machine.

Once the quote goes, the follow-up is the same as for any quotation; our post on quotation follow-up covers it, and so does quotation and proposal follow-up. Seals add one call of their own: ask after fitting whether it held.

For example: a Nagpur rubber shop and a baling press

Imagine a rubber products shop in Nagpur that gets a photo from a cotton ginning and pressing factory in Vidarbha, in the thick of the season. The hydraulic cylinder seal on the baling press has split. The details are illustrative. The owner sizes it from the photo against the fitter's thumb, guesses nitrile, and quotes a mould because the part looks moulded. Two days go in messages. The factory's fitter buys a seal from a hydraulics shop in the market and fits it that evening.

The shop's mistake was answering before it asked. It now sends the five questions as its first reply. When the same factory writes again the next season, the fitter answers all five: hydraulic oil, about 60 °C at the seal, high pressure, a moving rod, and a groove measured with a vernier. Two are needed now and ten for spares. The shop turns two polyurethane seals from tube stock on its seal-cutting lathe, with no tool. It quotes the ten as a moulded part with the mould on its own line, and both prices go out in the first reply.

When to send the enquiry elsewhere

Some seals are not yours to quote. Food, drinking water, medical and gas applications can call for compounds with specific approvals, and the rules differ by use and change. The buyer's engineer or adviser decides what is needed, and you quote only compounds whose papers you hold. High-pressure moving seals beyond your range go to a specialist, with a name if you have one.

And some enquiries are rate collection. If the sender will answer none of the five and wants only "best rate", give a range with its assumptions and move on.

Make the five questions your first reply

Put the five questions into a quick reply today. Use it on the next photo. Keep each set of answers in one sheet, since it shows what your buyers' machines need and what spares to offer. The rest of the rubber shop's selling job is on the rubber products page. To set up the reply, the sheet and the follow-up together, tell us what you need.