From Sample Electric Motor to Series Order in Machine Building: How Do You Keep Technical Compatibility?

When moving from a sample motor to series orders, the safest way to keep technical compatibility is to turn the approved sample into a written reference record and compare every series order with it. Matching power and speed is not enough; the frame material, IEC frame code, mounting arrangement, flange size and voltage connection must stay the same as well. If one of these changes silently, the problem usually appears on the machine assembly line, when the motor does not fit.

This article is for manufacturers who build their own machines and buy the motor as a component. It is not about choosing a motor for a single machine, but about supplying the same motor repeatably for dozens of machines.

Which information should you freeze when the sample is approved?

When the sample motor is fitted to the trial machine and run, the team actually holds a design decision. That decision contains more information than the motor nameplate and the order line. Write at least the following into the reference record:

• Model code and power: e.g. 100L2-4, 3 kW. The code describes the IEC frame and the number of poles together.
• Frame material: aluminium or cast iron. It is not part of the code, so it must be written separately.
• Mounting arrangement and flange: B3, B5, B14, B34, B35 or vertical; if flanged, the size of the part it mates with on the machine.
• Voltage and connection: the voltage on the nameplate (230/400 V or 400/690 V) and the connection used on your machine (star or delta).
• Starting method: direct-on-line, star-delta or frequency inverter.
• Layout details: the position of the terminal box on the machine, the cable entry direction and the part the shaft end connects to (coupling, pulley, gearbox input).

Instead of writing dimensions (shaft diameter, flange, foot hole spacing) into the record by hand, note the name and revision of the relevant 2D technical drawing. That way, any discussion about dimensions is based on the same document, not on two people reading a ruler.

Why is the model code alone not enough?

At HEM Motor, the model code does not change with the frame material. For example, the code 112M-4 is used for both the aluminium and the cast iron frame model with 4 kW and a rated speed of 1,450 rpm; the electrical values are identical. If purchasing writes only "112M-4" on the order, the motor delivered may not be made of the same material as the sample. When the frame material changes, the motor's weight and appearance change; if your machine's supporting structure, cover design or customer expectations are sensitive to this, the frame must be stated on the order line.

Another limit is the power range. Aluminium frame models cover 0.25–11 kW and cast iron frame models cover 0.55–355 kW. So a 0.25 or 0.37 kW sample cannot be switched to cast iron for the series, because the standard list on sale has no equivalent; if this need exists, it should be asked about separately.

What changes when the power changes within a machine family?

In series production, the same machine comes in small and large versions. Approving the sample at 3 kW and moving to 4 kW for the large version seems natural, but more than the power changes at this step:

Because the frame moves from 100L to 112M, the foot and flange dimensions differ; the base and motor plate must be drawn separately for each version. The difference on the voltage side is easier to miss. Star-delta starting on a 400 V supply requires the motor to be connected in delta on that supply; the 4 kW model rated 400/690 V is therefore suitable for it, while the 3 kW model rated 230/400 V is connected in star at 400 V and is not suitable for star-delta starting. The panel diagram and the terminal connection instruction should be prepared separately for each version.

Mounting and flange: the most common deviation

The item that causes the most trouble in series orders is the flange. Calling a flange simply "B5" or "B14" does not prove that it matches the connection size on your machine. Mounting options (B3, B5, B14, B34, B35 and vertical V1/V3/V5/V6/V15) are offered according to the frame and the flange size is confirmed with the order; details are summarised in the mounting arrangements question. Match the size of the flange used on the sample with the 2026 technical and product catalogue, write it into the reference record and repeat the same wording in every series order.

You can review suitable models from the standard range and current prices on the buy electric motors page.

What should be checked when the first batch arrives?

The reference record becomes a checklist at first-batch acceptance. You do not need to dismantle every motor; on the first few motors, the following comparison gives enough information:

• Are the model code, power, rated speed and voltage on the nameplate the same as on the sample?
• Do the frame material and mounting arrangement match the order line?
• Do the flange and shaft end seat on the mating part of the machine without force?
• Is the terminal box position compatible with the cable route on the machine?
• In a short no-load run, are the direction of rotation and the sound similar to the sample?

If you find a difference, report it before series assembly begins; if the difference comes from the order wording, correct the reference record too.

Hypothetical example: a packaging machine manufacturer

The following flow is a hypothetical example. Suppose a packaging machine manufacturer has approved, on its standard model, an aluminium frame 100L2-4 motor with 3 kW and 1,500 rpm synchronous speed, connected to a gearbox with a B14 flange. The new large model requires 4 kW.

• The engineering team selects the 112M-4 model and checks on the drawing whether the gearbox input flange fits the 112M frame.
• The panel team marks on the diagram that the motor is now rated 400/690 V and will be connected in delta on the 400 V supply.
• Purchasing writes on the order line: "112M-4, 4 kW, aluminium frame, B14, flange size as in the reference record".
• In the first batch, two motors are checked against the list above, then series assembly starts.

Example models for series supply

• 90L-4 aluminium frame: 1.5 kW, 4-pole, 1,445 rpm, IEC 90L, 230/400 V. For small conveyors and auxiliary drives.
• 100L2-4 aluminium frame: 3 kW, 4-pole, 1,450 rpm, IEC 100L, 230/400 V. The sample model in the example.
• 112M-4 aluminium frame: 4 kW, 4-pole, 1,450 rpm, IEC 112M, 400/690 V. In the large version, watch the frame and voltage change.
• 112M-4 cast iron frame: the same electrical values; if your machine is going to a dusty or vibrating site.

You can see the general-purpose industrial range on the industrial motors page.

Conclusion: information to send for a series order

Series supply means repeating the decision made on the sample with the same words in every order. When requesting a quote, send the model code, power, speed, frame material, mounting arrangement and flange size, voltage and starting method from your reference record, together with the estimated annual or per-batch quantity. Review suitable models and current prices on the buy electric motors page. Send a photo of your current motor's nameplate, its speed and mounting details via the send motor nameplate page and request a quote for the right model. For other questions, you can use our contact page.

Frequently Asked Questions

Are two motors with the same model code always interchangeable?

The electrical values are the same, but the frame material and mounting arrangement may differ. In the order, write the frame material and flange size next to the code.

Can I replace the 230/400 V motor used on the sample with a 400/690 V model in the series?

The change is possible, but the connection changes: on a 400 V supply, a 230/400 V motor is connected in star and a 400/690 V motor in delta. The panel diagram and starting method must be updated accordingly.

How should I describe the flange size in the order?

Writing only B5 or B14 is not enough. Compare the size of the flange that matched on the sample with the catalogue and technical drawing and use the same wording in every order; the size is confirmed with the order.

How many motors should I check in the first batch?

There is no fixed number; checking the nameplate, mounting and connection on the first few motors usually catches a deviation. You can increase this number depending on how critical the machine is.