A Cost Controller's 6-Step Checklist for Gearmotor Procurements in 2025

If you're buying gearmotors for a plant or a product line, the difference between a 'cheap quote' and the minimal total cost of ownership is usually hidden in details the sales rep won't volunteer. This is a checklist for anyone who has to approve the PO — no theory, just the steps I use before I sign off.

It applies to any gearmotor supplier. But because SEW-Eurodrive is one of the brands I've bought and maintained for the past decade, I'll use it as a reference point.

Before the steps, one disclaimer: I'm a cost controller, not a design engineer. My perspective is about what happens after the part is installed — the maintenance, the spare parts, the downtime that isn't on the invoice.

Step 1: Define the duty cycle before you start looking at part numbers

A gearmotor is not just torque plus speed. The same 2.2 kW gearmotor that works on a conveyor running 12 hours a day can fail quickly on a press that starts and stops 50 times per hour. You need the duty cycle: starts per hour, operating hours, ambient temperature, and the inertia ratio of the driven load.

For example, a recent automation cell in our company needed a positioning drive. The initial RFQ specified a servo motor. But once we looked at the actual motion profile, a small stepper motor was enough — the load was light and the move took less than a second. The same thinking applied to a fitness gear rack adjustment on a new piece of exercise equipment: a small stepper motor gave us the repeatability without paying for continuous torque we'd never use.

That's not a popular thing to say in a world of incremental encoder hype, but in my experience, duty cycle is the first thing people fudge.

Step 2: Calculate total cost of ownership, not the sticker price

When I audit past purchases, I still find surprise costs: freight, special flanges, mounting adapters, oil coolers, engineering reviews. A 10% lower quote can disappear in a day.

Here's a real example from our cost tracking system. We compared two 1.5 kW helical gearmotors for a conveyor upgrade. One supplier quoted $1,450. Another supplier quoted $1,220, but then added $320 freight and a $180 handling fee — maybe $150, I don't have the invoice in front of me. The second total came to $1,690. That's about 17% over the first quote. And the first quote included a commissioning checklist from the manufacturer.

The numbers said go with the second supplier. My gut said something else: their support line went straight to voicemail on the second call. We went with the first, and six months later the second supplier closed its regional office. That's the kind of thing you can't put in a spreadsheet.

Since then, our procurement policy requires quotes from at least three vendors and a TCO calculation that includes spare parts and service response time.

Step 3: Confirm the gearbox oil type before you finalize the PO

One of the most under-appreciated variables in TCO is the lubricant. SEW-Eurodrive gearbox oil type is not something you can guess from the outside. It depends on gearbox frame, reduction ratio, input speed, mounting position, and operating temperature.

If you search 'SEW-Eurodrive gearbox oil type,' you'll find a lubricant table in the manual — but it's only useful if you have the exact model and serial number. In many SEW units, the standard recommendation is a synthetic polyalphaolefin-based oil in an ISO VG 220 or 320 grade. That's the majority, not all. In low-temperature applications, you may need a lower viscosity. In high-temperature environments, a higher-grade or synthetic ester might be required.

Reference: ISO 3448 defines viscosity grades for industrial liquid lubricants; the number is the kinematic viscosity at 40°C in mm²/s. An ISO VG 220 oil has a mid-range viscosity of 220 mm²/s.

I still kick myself for not checking oil type on a small batch of reducers we bought in 2023. We filled them with a mineral product and within a year the noise level was noticeably higher. The re-labour cost was five times the price difference of the correct oil.

Quick tip: get the oil type and quantity in writing on the quote. If the seller can't specify it, assume you'll have to pay for an engineering call.

Step 4: Decide if you need a VFD — and know what it changes

First, the question that still comes up on every buying committee: what's a VFD? A variable frequency drive controls the speed of an AC motor by adjusting the voltage and frequency supplied to it. It gives you controlled acceleration, softer starting, and often better energy efficiency than a fixed-speed starter.

But you don't always need one. For a pump that runs at a fixed speed, a contactor is enough. For a mixer where the operator needs to change speed from batch to batch, a VFD is almost always worth the extra money. And for a high-inertia load, a VFD can avoid the mechanical shock of across-the-line starting.

The old 'when in doubt, oversize the motor' thinking comes from an era when starting was hard and VFDs were expensive. Today, that thinking is outdated. Oversized fixed-speed motors run less efficiently, and a properly sized motor with a VFD often costs less in the long run. That said, a VFD adds complexity — harmonics, cabling, parameter settings — so it shouldn't be installed just for the sake of it.

Step 5: Check local support and market strength

Before I buy an imported gearmotor, I look at the vendor's local footprint. Public reports on SEW-Eurodrive Japan market share for gearmotors are scarce, but the company's presence in Japanese automation lines paints a clear picture. In the gearmotor segment, they're a strong outside player, particularly in automotive welding and material handling.

When we had a line expansion in Tokyo, the deciding factor was not the catalogue spec. It was the fact that SEW-Eurodrive Japan has a local engineering team that answered mounting and compatibility questions within a day. The lead time from the factory was the same as other European suppliers, but the local support made the difference.

In my experience, support response time is a better predictor of future pain than the motor's price.

Step 6: Demand documentation before you approve the order

A reliable supplier can produce manuals, wiring diagrams, dimension drawings, and oil specification sheets without a week of follow-up. We use that as a test. If a vendor can't quickly provide a PDF manual for the exact model, the after-sales experience will probably be worse.

For SEW-Eurodrive, a lot of this is online: gearmotor manuals, VFD parameter lists, and even 3D CAD files. When I look up a part number, I want to see the output shaft dimensions, the oil fill plug location, and the thermal rating. If the documentation is scattered or missing, I put that vendor on the 'risk' list.

It also helps to check the manual before you accept the delivery. We've got about 40 SEW units in our plant — maybe 45, I'd have to count in the CMMS — and the ones that had the right documentation from day one were the easiest to maintain.

Final notes: common mistakes I see in purchase orders

• Assuming one oil works across your whole fleet. Gearbox oil type needs to match each unit's specification.
• Oversizing to compensate for the lack of a VFD. You end up paying for energy waste every month.
• Believing 'zero maintenance' — every gearmotor has seals, bearings, and oil that need attention.
• Comparing an incomplete quote from one supplier with a complete solution from another. Make the scope identical before you compare prices.

This checklist isn't exhaustive, but it will stop the most expensive surprises. The cheapest quote is rarely the cheapest installed cost. If it feels like the vendor is being vague, they probably are.