A mold heat-treatment report should identify the component, the processing route and the actual inspection results. A steel grade followed by one hardness number is not enough to explain what happened to a finished insert. Agree on the evidence package before heat treatment, including test locations, acceptance limits, dimensional checks and the treatment of later repairs.
This guide is for engineers and buyers reviewing outsourced tooling. It addresses release evidence after the material has been selected, rather than recommending one universal hardness for every mold. Include these requirements when discussing mold making with FUMING or reviewing a toolmaker’s manufacturing plan.
Identify which material route applies
First determine the steel’s delivery condition and the intended processing route. A prehardened mold-base material, a steel supplied for subsequent hardening and tempering, and a precipitation-hardening grade do not necessarily follow the same sequence. Avoid demanding a generic “hardening certificate” for a route that was never specified.
As a material-specific example, Uddeholm describes RoyAlloy as supplied prehardened. Separately, its Corrax product information identifies an aging-based hardness response. These examples illustrate why the named grade and delivery condition must be matched to the correct manufacturer’s guidance; they are not recommendations for every mold.
Make a component list that distinguishes cavity inserts, cores, slides, wear elements and mold-base plates. The same assembly can contain different materials and acceptance requirements. Do not apply the most demanding insert specification to every plate, or accept a general mold-base document as evidence for a separately processed cavity.
Connect the component to the processing batch
Record the tool number, component identifier, drawing revision, material identity and heat-treatment batch reference together. If several visually identical inserts are sent out, establish a suitable identification method before dispatch. Identity must remain understandable after cleaning and finish machining, when earlier stock markings may disappear.
Ask who owns each record: the material supplier, toolmaker, heat treater or inspection laboratory. The final package should allow the buyer to follow those references without guessing. Where a subcontractor uses its own batch number, retain the cross-reference to the toolmaker’s component list.
A witness coupon also needs an identity and a stated relationship to the load. Its material, dimensions, position and processing history affect what it can represent. Do not treat a convenient spare piece as automatic proof of the properties throughout a large insert. Agree the purpose and limitations of any coupon before relying on its results.
What belongs in the report?
| Report section | Information to agree | Release question |
|---|---|---|
| Component identity | Tool, insert, revision, steel identity and processing batch | Does the record belong to this component? |
| Specified route | Approved process reference and required condition | Was the intended material route followed? |
| Process evidence | Required cycle records, dates and subcontractor reference | Can the responsible specialist assess processing against the specification? |
| Hardness results | Method, scale, locations and individual readings | Do valid results satisfy the agreed limits? |
| Subsequent operations | Grinding, EDM, repair welding or surface treatment, where relevant | Does the evidence describe the final condition? |
| Disposition | Deviations, retests, approvals and release status | Is the component accepted, held or awaiting a decision? |
Define hardness acceptance before testing
Specify the hardness range and scale for each controlled component on the approved documentation. A bare value such as “50” is incomplete. Also identify when the requirement applies: after a particular thermal cycle, after final grinding, or after a later surface treatment. Results taken at different stages may answer different questions.
ASTM E18 covers Rockwell hardness testing of metallic materials. Use the complete applicable method and the contractually required edition. A public scope page is useful for identifying the method, but it does not provide the complete testing procedure or acceptance criteria for your tool.
Decide how many locations and readings are needed for the component and its risks. Record individual values as well as any permitted summary. An average can obscure an outlying location; do not average away a reading that requires investigation under the agreed acceptance rule.
Plan locations that produce meaningful results
Mark approved test regions on a simple component sketch. Keep impressions away from working surfaces where damage would affect the molded part or tool function. The test specialist must check suitability of the available material thickness, support, surface condition, spacing and method for the chosen locations.
Buehler’s Rockwell testing guidance explains that specimen condition, secure support, cleanliness and movement affect results. Consequently, an unexpected reading should trigger a review of the test setup as well as the material. Retesting under controlled conditions should preserve the original result and explain the reason for the repeat.
If a finished cavity has no suitable test area, resolve that constraint before machining reaches its final state. A prepared pad, suitable companion specimen or another qualified test plan may be needed. The chosen solution must be accepted by the responsible specialist; testing an easy-to-reach but unrelated surface is not a substitute for planning.
Review the thermal route with a qualified specialist
Request the process evidence needed by the approved specification, rather than collecting a chart that nobody reviews. Identify the relevant cycle or procedure reference and any exceptions. If a chart is required, confirm how it is linked to the actual load and how the heat treater interprets it.
Uddeholm’s tool-steel heat-treatment guide discusses hardening, tempering and dimensional stability. It provides useful technical background, but production parameters must be chosen for the actual grade, geometry and equipment. Do not copy temperatures or times from a different grade’s brochure into a purchase order.
Ask the heat treater to flag unusual section changes, processing constraints or deviations before proceeding. The buyer’s role is to define the required condition and approval route. The specialist’s role is to establish a suitable process and assess whether the records demonstrate that it was achieved.
Hardness and dimensional acceptance are separate checks
An acceptable hardness reading does not establish that a mating face remains flat or that a slide still fits its guide. Compare relevant dimensions and geometry at the agreed manufacturing stages. Keep the inspection datum scheme consistent enough that a reported change can be interpreted.
Decide which dimensions are intentionally left with finish allowance and which must be accepted after thermal processing. Record the final grinding or machining revision. If a component needs correction, retain the earlier record rather than presenting the corrected result as if it were the original condition.
For near-limit inspection disagreements, use a defined acceptance process; the measurement uncertainty guide explains why a number close to a limit needs context. That dimensional decision does not replace material or heat-treatment acceptance.
Account for later EDM, welding and surface treatment
Heat-treatment records can become incomplete when later work is omitted from the history. List operations performed after the reported test. Ask the steel supplier or responsible specialist whether any subsequent thermal or inspection step is required for the grade and operation concerned.
For example, Uddeholm’s Unimax heat-treatment guidance includes grade-specific guidance concerning stress tempering after EDM or specified welding. This illustrates the need to consult the correct document; it is not a universal instruction to retemper every steel after every operation.
The mold EDM electrode review addresses a different process decision. Whichever electrode is selected, the final tooling record should identify the completed operations and any required follow-up, rather than stopping at the date the insert returned from the heat treater.
Use a controlled hold-and-release decision
Consider two otherwise identical inserts whose reports list an acceptable value but no test locations. This is an illustrative review scenario. The missing information is not proof that the inserts are defective, but it prevents the reviewer from understanding the evidence. Request the original test details and agree any necessary additional assessment before release.
Keep “information missing,” “test validity in question,” and “confirmed nonconformance” as separate statuses. Each calls for a different response. Retain the component identity, open questions, responsible person and approval record. Do not create a replacement certificate that hides a deviation or an unresolved test result.
Include the accepted records in the tool handover package. The mold transfer checklist explains the broader documentation needed when a tool changes location. Send component drawings and the requested heat-treatment evidence with a FUMING tooling enquiry so the scope can be reviewed before manufacture.
Frequently asked questions
Is the highest hardness always the best choice?
No universal value suits every steel and mold component. Use the approved material and application requirements, with the steel supplier and tooling specialist involved in selecting the condition.
Can one witness coupon release every insert in a batch?
Only if the agreed inspection plan establishes what that coupon represents and what additional checks are required. Its presence alone does not prove every location in every component.
Should a surprising result be deleted after a passing retest?
No. Preserve the initial result, the reason for retesting, the revised setup if any, and the authorized disposition. That history makes the final acceptance decision understandable.
