Why this matters
Two injection molding quotes for the same part can differ by a large margin without either being wrong, because they rest on different assumptions about cavities, cycle time, resin, samples and who pays for changes. Put every quote on the same basis before comparing the number at the bottom.
Why a lower number is not always a lower price
A quote is a bundle of assumptions with a total on top. One supplier may price a 2-cavity mold with a short cycle and a generic resin, another a 4-cavity mold with a tighter cooling layout and a named grade, and each total is correct for its own assumptions. Comparing totals without comparing the assumptions turns the quote stage into a guess about which supplier will add charges later, so the useful first step is to list what each quote assumed.
Tooling: cavities, steel and guaranteed life
Ask for the number of cavities, the steel family, the hardness, the expected life in shots and whether texture, sliders or lifters are included. A mold priced low because it uses softer steel or fewer cooling lines may be fine for a few thousand parts and a poor fit for a long program. Also ask who owns the mold and what happens to it at the end of the program, because ownership and the right to move the tool are part of the price you are agreeing to.
Part price: cycle time, cavities and what it includes
The unit price follows from cycle time, cavity count, machine rate and material weight, so ask each supplier to state the cycle time and machine tonnage it assumed. Then check what the part price includes: runner and sprue treatment, degating, flash trimming, secondary operations such as pad printing or ultrasonic welding, inspection, packaging and labeling. A part price that excludes finishing steps another supplier included is not lower, it is incomplete.
Resin: grade, price basis and color
State the resin family, the exact grade or an approved equivalent, the color requirement and any certificates needed. Resin prices move, so ask whether the quote fixes the price, indexes it or reserves the right to adjust it, and whether the part weight assumed includes runner scrap. A quote built on a general resin can look cheaper than one built on the grade you actually need.
Samples, corrections and who pays for changes
Ask how many T1 samples are included, how many correction rounds are covered in the tooling price and what a design change after T1 costs. Mold corrections that come from a supplier error should not be billed, but changes you request will be, and the rate for those changes belongs in the quote. This is the line that most often turns a low tooling price into a high project total.
Volume, price breaks and the total cost of the first order
Ask for prices at your first order, your expected annual quantity and a lower and higher volume, so you can see where the price breaks sit. Then add the items that sit outside the part price: freight and duties, packaging, the cost of a sample round and any minimum order. A comparison across suppliers should end in one number, which is the cost of tooling, one correction round and the first production order delivered, not the unit price alone.
Line-by-line quote comparison
| Quote line | What can differ between suppliers | What to ask so quotes match |
|---|---|---|
| Tooling | Cavity count, steel, hardness, mold life, texture, sliders, ownership | How many cavities, which steel and hardness, expected shots, what is included and who owns the mold? |
| Part price | Cycle time, machine tonnage, material weight, included operations | Which cycle time and press size were assumed, and which finishing and inspection steps are in the price? |
| Resin | Generic family vs named grade, color, certificates, price basis | Which grade and color, fixed or indexed price, and is runner scrap in the weight? |
| Samples and changes | Number of T1 samples, correction rounds, change-order rate | How many samples and corrections are included, and what does a design change cost? |
| Volume breaks | Price at first order, annual volume, MOQ | What are the prices at three quantities and what is the minimum order? |
| Packaging and freight | Pack method, labeling, incoterm, freight and duties | What is included in the price and which incoterm applies? |
| Lead time | T1 date, production lead time, delivery after approval | Which dates are tied to deposit, drawing freeze and sample approval? |
What every supplier should state in writing
Practical takeaway
Compare quotes only after each one has been rewritten on the same assumptions: tooling specification, cycle time, resin grade, included operations, sample rounds and the price at your real volumes. The supplier that is willing to list those assumptions in writing is usually the one whose number you can rely on.
How to apply this guide
Use this guide as a preparation step before asking for mold price or production lead time. A stronger RFQ names the current project stage, the file format available, the expected first order, the annual volume, the target resin and the approval evidence needed after T1 samples.
If the project is still early, the guide can also show whether the next move is design cleanup, rapid tooling, production mold planning, material selection or quality-document scoping. That makes the inquiry more specific and helps the first engineering reply focus on decisions instead of basic clarification.