A supplier receiving an enquiry for “PP spool, 400 mm flange, quote please” has two options: ask twelve questions, or make assumptions and hope. Many suppliers will take the second route, because asking questions slows the quote down and might lose the order. That is how you end up comparing three quotes for three different products.
Twelve pieces of information turn a vague enquiry into a comparable one. They are not onerous — most are already known to somebody on the production floor.
The product
- Product type and construction. Cable, wire, rope, hose, tape, fibre, filament. The material matters less than the behaviour.
- Overall diameter, including any armour, jacket ribs or serving. Nominal diameter is the most common source of capacity errors.
- Minimum bend radius, if the product has one. This sets the core.
- Weight per unit length, or the total weight per spool. This sets the flange.
The duty
- Winding tension, and whether it is constant or tapered.
- Maximum payoff speed, in rpm, so balance can be specified against something.
- Payoff method — tangential, over the flange, driven or braked.
- Length per spool, and whether that is a hard requirement or a preference.
The geometry
- Flange diameter and traverse width, and which of these are fixed by your equipment.
- Core or bore diameter, with the shaft or spindle dimension and its tolerance.
- Any constraint — pallet pattern, container height, rack opening.
The commercial and service conditions
- Quantities, trip target, and the environment — including whether the spool will be washed, stored outdoors, or exposed to anything unusual.
Two things that make quotes comparable
Ask for the same thing from everyone. If one supplier is quoting a ribbed flange and another a flat one, the prices are not comparable and neither are the products. State what you want, or ask each supplier to state what they are quoting.
Ask what is assumed. A good supplier will list their assumptions on the quote — tension, temperature, cycle life, tolerance. If they do not, ask. Those assumptions are where the disappointment lives.
What not to over-specify
Tolerances that do not matter. A bore tolerance of a hundredth of a millimetre on a hand-loaded spool is paying for precision you cannot use, and it will show up in the price. Ask which dimensions are functionally critical — usually the bore, the flange seating faces, and the product contact surfaces — and hold tolerance there while leaving the rest open.
Similarly, do not specify the material grade unless you have a reason. Tell the supplier the duty and let them propose the grade; you will often get a cheaper spool that performs the same.
The one question worth asking
“Where do you expect this spool to fail?” A supplier who has thought about it will answer immediately — at the rim, at the bore, at a fold line — and that answer tells you more about the design than any datasheet.
A supplier who cannot answer has not tested the design, and you will be doing the testing for them.
Send us the twelve items above and you will get a quote that means something, and a spool that behaves the way you expect.
What to leave out
Over-specification is as much of a problem as under-specification, and it shows up on the quote. Three things to consider leaving out unless they genuinely matter:
- Tolerances copied from a different application. Tight tolerance costs money, and a tolerance you do not need is pure cost.
- Finish and appearance requirements on a spool that will spend its life in a yard.
- A material call you are not sure about. If you specify a grade because it worked somewhere else, say what you are trying to achieve instead and let the supplier propose. You may get a better answer and a cheaper one.