Reviewed by: Technical Engineering Department – TGB Group Published: June 2026 Technical review: June 2026

In most rotary projects there is a moment when the same question appears: do we specify a standard slewing ring or slewing drive, or do we go for a custom solution? The answer is rarely obvious, and the way it is decided has consequences that go well beyond the component itself. It affects reliability, cost, lead time and how the equipment behaves over its full service life.

Customisation is often discussed as if it were always an improvement, a way to obtain a product perfectly tailored to the application. In practice, it is a trade-off. A well-justified custom solution can deliver real gains in performance, integration and reliability. A poorly justified one introduces cost, complexity and risk without solving a real problem. And every customisation introduces engineering risk. The objective is not to eliminate that risk, but to ensure that the value created exceeds it.

This article looks at when customising a rotary solution genuinely makes sense, when a standard product is the more sensible choice, and how each option influences reliability and overall cost.

What “custom” really means in a rotary solution

Customisation in slewing systems is not a binary choice between catalogue and bespoke. Most projects fall somewhere along a spectrum:

• Pure standard. The product is selected from a catalogue series and integrated as supplied.
• Configured standard. A standard product is selected with specific options such as motor type, shaft configuration, sealing class or mounting interface. The architecture is unchanged.
• Modified standard. A standard product is adapted with specific dimensional, material or interface changes while keeping its core design.
• Custom-engineered solution. The product is designed or significantly redesigned to meet a particular technical requirement that the standard range cannot cover.

The four levels carry very different implications. A configured standard delivers nearly all the field experience of the base product. A custom-engineered solution may deliver performance no standard could match, but it does so with new variables that need to be validated.

The first decision in any project is not “custom or standard.” It is “which level on this spectrum is justified by the requirement, and why.”

Why standard product ranges exist in the first place

Standard product ranges are not a limitation. They are the result of accumulated engineering knowledge. A mature catalogue, like the one TGB Group has developed across its slewing drive series — BE Standard, LBE Light, TE, TGO Open, TVR Vertical Solar, MultiDrives, Double Worm and DAD Double Axis — covers a wide range of load, speed, torque and environmental requirements found in industrial applications.

Each standard model carries the benefit of repeated production, accumulated field data, validated tolerances and a known maintenance behaviour. That history is a form of engineering capital. When an application fits the operating envelope of a standard range, choosing it is not a compromise — it is the decision that maximises predictability.

The mistake is to default to customisation as if it were a sign of higher engineering quality. In rotary solutions, the opposite is often true: the higher engineering decision is to verify whether a standard product can do the job before committing to a custom design.

When customisation genuinely makes sense

There are a number of situations where the standard range will not cover the requirement, and customisation becomes the rational choice. The most common are:

• Loads or moments outside the standard envelope. When the application exceeds the rated capacity of every standard model, or sits in a combination of axial, radial and moment loads that no standard product is optimised for.
• Non-standard dimensional or interface constraints. When the machine architecture imposes a specific bore, mounting bolt pattern, height, shaft type or motor flange that no standard model provides.
• Environmental requirements beyond standard specifications. Operation in extreme temperatures, aggressive atmospheres or chemical environments where standard sealing, lubrication or surface treatment is not sufficient.
• Specific performance characteristics. Applications requiring particular backlash classes, defined holding torque, precise positioning behaviour or specific dynamic response that go beyond what the standard range delivers.
• High-volume series with specific integration needs. When the same equipment will be produced in significant volumes, a custom solution can reduce assembly time, simplify integration and lower the total cost per unit over the life of the project.
• Strategic differentiation. When the equipment manufacturer needs a unique solution that competitors cannot replicate from a standard catalogue.

In these cases, customisation is not a luxury. It is what makes the project technically viable, or commercially competitive over time.

When a standard product is the better answer

Equally important is recognising when customisation is the wrong response to the problem. The most common situations are:

• The requirement can be met by a configured standard. Many specifications that initially look custom are actually combinations of catalogue options. A correct selection process often resolves them without redesign.
• The “custom” requirement comes from incomplete application engineering. When the standard product seems insufficient because the loads, moments or duty cycle have not been calculated correctly, customising the product hides a problem upstream rather than solving it.
• Project volume does not justify the engineering effort. Custom development carries fixed engineering and validation costs that need to be spread across the units produced. For low-volume or one-off projects, those costs can outweigh any performance benefit.
• The advantage gained is marginal. When the custom solution delivers a small improvement over a standard product, the additional cost, lead time and risk rarely pay back over the life of the equipment.
• Time-to-market is critical. Custom-engineered solutions take longer to design, validate and produce. When the project schedule does not allow that time, a well-selected standard product is the more reliable path.

In these cases, choosing a standard product and investing the engineering effort in correct selection and integration delivers better outcomes than commissioning a custom design.

Quick reference: situation and recommended approach

 

How customisation affects reliability

Reliability in a rotary solution comes from two sources: the inherent design quality of the product, and the field experience accumulated over many units operating in real conditions. Customisation changes the balance between these two.

A custom-engineered solution can be more reliable than a standard one when it eliminates compromises that a generic product had to accept. A drive designed specifically for a known load case, environment and integration constraint can operate further from its limits than a standard product asked to cover a wider envelope.

But a custom solution also starts with less field history. Where a standard product behaves as decades of operation have shown it will, a custom product behaves as the engineering analysis and validation testing predict it should. The gap between prediction and reality is bridged through engineering rigour: load calculation, finite element analysis, prototype testing and validation under representative conditions.

This is why the reliability of a custom rotary solution depends less on the fact that it is custom, and more on how it is engineered. Customisation supported by full calculation, prototype testing and component validation can match or exceed standard reliability. Customisation without that engineering effort behind it carries real risk that the standard product would not have.

How customisation affects cost

The cost impact of customisation is often misunderstood because it is evaluated only at the level of unit price. The full picture has four components:

• Engineering and design cost. The hours required to define, calculate, simulate and validate a custom design. This is a one-off cost that does not scale with volume.
• Tooling and setup cost. Specific fixtures, machining setups or assembly tooling required to produce a non-standard part.
• Unit production cost. The cost per unit of manufacturing the custom solution, compared to a standard product produced in series.
• Total cost of ownership. Maintenance, spare parts availability, downtime cost, and the operational benefit or penalty of using a custom product over the life of the equipment.

For low-volume projects, engineering and tooling costs dominate, and a custom solution is rarely competitive against a standard product unless the application strictly requires it. For high-volume projects, the fixed engineering costs are spread across many units, and the gains in unit cost, integration time and operational performance can make custom solutions clearly more economical.

The decisive question is not “is the custom version more expensive than the standard version?” It is “across the full lifecycle of the equipment, which option delivers the lower total cost while meeting the technical requirements?”

Common mistakes in the customisation decision

Most problems in the custom-versus-standard decision trace back to the same recurring patterns:

• Specifying customisation before completing a rigorous selection exercise against the standard range.
• Treating customisation as a way to compensate for incomplete load calculation or unclear duty cycle definition.
• Evaluating cost only at the unit price level, without considering engineering, tooling and total cost of ownership.
• Underestimating the lead time and validation effort that a custom solution requires.
• Assuming that “custom” automatically means “better” without defining what is actually being improved.
• Customising in low volumes when a configured standard would have met the requirement.

None of these is an argument against customisation when it is justified. They are arguments for making the decision deliberately, with full visibility of what each option implies.

A framework for deciding

A useful sequence to make the decision in a structured way:

1. Define the requirement precisely. Loads, moments, speeds, duty cycle, environment, interfaces, performance and lifecycle.
2. Map it against the standard range. Identify which standard products could potentially cover the requirement, with or without configuration options.
3. Check what does not fit. If gaps remain, identify exactly what cannot be covered by a standard product and why.
4. Quantify the gap. Is it a small adjustment that justifies a modified standard? Or a fundamental mismatch that requires custom engineering?
5. Evaluate volume and lifecycle. Consider production volume, project timeline, total cost of ownership and the cost of not meeting the requirement perfectly.
6. Decide deliberately. Pure standard, configured standard, modified standard, or custom-engineered solution, with the reasoning documented.

Following this sequence does not guarantee the cheapest choice, but it does guarantee the most defensible one — the one that can be explained to engineering, operations and finance with the same answer.

How TGB Group approaches customisation

With more than 30 years of experience in motion solutions, TGB Group works across the full spectrum described in this article. The company offers an extensive catalogue of standard slewing drive series and slewing rings that covers the majority of industrial requirements, and an in-house engineering department that supports customers in selecting the right configuration, modifying a standard product when needed, or developing fully custom-engineered solutions when the application calls for it.

TGB’s full-service engineering combines four capabilities: new design development for continuous improvement of performance and efficiency, customisation of standard products to customer specifications, technical support during the selection and integration process, and validation through testing under demanding conditions. Calculations are made with dedicated design software and cross-checked against tables developed in collaboration with external engineering companies, so that the result complies with the parameters indicated in the sales drawings.

This combination — a mature catalogue plus engineering capability to customise when justified — is what makes the standard-versus-custom decision a real choice rather than a forced one.

If you are evaluating whether your application calls for a standard or a custom rotary solution, TGB Group’s technical team can review your requirements and help define the right level of customisation for your project. Contact our technical team to define the right solution for your project.