Decide what you are replacing and why
An obsolete part, a long lead time and a new machine design are different purchasing problems. Record the reason for the enquiry before comparing products. For a breakdown, preserving the existing installation may dominate the decision. For a new platform, a wider design change could be reasonable if the performance, integration effort and supply route are acceptable.
An original part should remain an option where it fits the requirement. Ask for original-part sourcing and an alternative assessment together when both are useful. Send the current model for pricing and sourcing or configure a new requirement.
Use an evidence ladder
| Description | Evidence expected | Outstanding work |
|---|---|---|
| Same product category | Similar function or technology | Almost all application checks |
| Published specifications compared | Relevant figures for clearly identified models | Conditions, interfaces and installed duty |
| Application assessed | Requirements and integration differences reviewed | Agreed verification and commissioning |
| Tested configuration | A documented test on the identified combination | Confirm that the customer’s installation matches the test scope |
Do not treat these descriptions as interchangeable. A manufacturer’s compatibility list can help narrow the search without guaranteeing that every motor, drive, feedback and firmware combination works. Likewise, a high series-level torque figure does not establish the continuous performance of a specific model.
Compare equivalent operating conditions
Separate continuous, intermittent and peak values. Record the cooling arrangement, operating temperature and duty assumptions behind the ratings. For positioning, consider the required motion and installed accuracy rather than selecting from resolution alone. Record which figures are missing instead of filling gaps with values from neighbouring models.
Check the interfaces that cannot change
Mechanical fit includes the envelope, mounting, shaft or output connection and accessory arrangement. Electrical integration includes supply, current, feedback and connectors. Control compatibility includes the command interface, network, firmware and configuration. Include environmental and documentation requirements relevant to the installed machine.
A dimensional match is useful but incomplete. A component can fit the mounting and still require different cables, a drive setting change or additional commissioning. Those differences belong in the recommendation and quotation, not in a footnote discovered after delivery.
Compare the full supply proposal
Ask each quotation to identify the exact model, options, accessories, documents, price and lead time. Include adapters, cables, engineering work and commissioning in the comparison where relevant. Clarify who supplies each item and what delivery and after-sales support are included. A cheaper component price can accompany a larger integration task.
For repeat OEM builds, specify expected volume, change-control needs and whether the proposed alternative is a second source or a permanent redesign. For a replacement, explain which existing components must remain in service. Confirm the basis of any stock or delivery statement when the quotation is issued.
What to send for an assessment
Send the full original code, current datasheet or nameplate photograph, associated components and the machine function. Add the duty, operating environment, quantities and required date. Identify unknowns and ask for the proposal to state the checks still outstanding. The replacement information checklist helps organise existing-machine enquiries.
Explore manufacturer alternatives, review motor-drive compatibility, or ask for engineering and sourcing support. We can help move from a shortlist to a defined supply enquiry, with the technical and commercial scope confirmed for the application.
Sources
Figures are summarised from the sources above and from manufacturers' published data on the date shown. Always confirm against the current datasheet for your exact part.