A GUIDE TO SUB-CONTRACT BALANCING

Sub-contract balancing is a professional service in which a specialist engineering company balances rotating components on behalf of other businesses. These parts are sent to the balancing provider, who then performs high-precision balancing using calibrated machines and certified procedures.

 

Our service supports a wide range of industries and component types, including:

Once balanced, components are returned ready for immediate installation or further assembly, complete with detailed balancing certificates and measurement data.

 

 

Use cases for sub-contract balancing

Sub-contract balancing is particularly valuable when:

Production volumes fluctuate
Outsourcing avoids idle investment in balancing machines during low-demand periods.

Component types vary
A specialist partner can handle different sizes, shapes, and weights on multiple machines.

Tight tolerances are required
Expert balancing facilities can achieve precision levels in line with ISO 1940/1 and other standards.

You’re developing prototypes
During design and R&D phases, it’s more practical to sub-contract balancing until volumes justify your own machine.

Your in-house machine is offline
Outsourcing provides continuity while equipment is being serviced or upgraded.

You want independent verification
Using a certified balancing service can validate or diagnose production issues.

 

Every reputable balancing provider follows a structured and traceable process. At CEMB Hofmann, our workflow typically involves:

 

Our clients provide details of the component including its dimensions, weight, operating speed, and balancing requirements. Drawings or CAD files can also be supplied to assist in setup.

 

The part is mounted on a calibrated horizontal or vertical balancing machine. Horizontal machines are ideal for long, shaft-based components such as rotors and armatures whereas vertical machines suit shorter, disc-shaped parts such as brake discs, fans, or impellers.

 

The component is spun at controlled speed, and any imbalance is precisely measured by vibration sensors and electronic instrumentation.

 

Material is added or removed (through drilling, milling, or weight addition) at exact positions to achieve the required balance grade.

 

The part is re-tested to confirm it meets tolerance specifications. Data is logged digitally and reviewed by a skilled balancing engineer.

 

A full balancing certificate is issued, detailing the component specifications, correction amount, and achieved balance grade, providing traceability for quality assurance systems such as ISO 9001.

 

 

Balancing is defined by ISO 1940/1, which specifies balance quality grades (G values). These represent permissible residual unbalance relative to the component’s mass and operating speed.

 

For example:

An experienced partner will recommend the correct grade for your application, ensuring safety and performance without unnecessary precision costs.

 

 

Choosing the right sub-contract balancing partner

Selecting the right provider can make the difference between smooth operations and recurring vibration problems. When evaluating a potential partner, consider:

1. Experience and expertise
Look for a company with decades of practical experience, ideally across multiple industries and component types. CEMB S.p.A for instance, for whom we are the UK operation, has been a leader in balancing for over 75 years.

2. Machine capability
Ensure the provider’s machines can accommodate your parts’ weight, size, and configuration. Our workshop handles everything from small rotors to components weighing several tonnes.

3. Calibration and certification
Confirm that all machines are regularly calibrated and traceable to national standards. The facility should also operate under a recognised quality management system.

4. Speed and flexibility
A good partner will offer fast turnaround times, often within 24 to 48 hours, and the flexibility to handle urgent or one-off jobs.

5. Technical support
The best providers act as technical partners, not just service suppliers. They’ll help diagnose vibration issues, recommend balance tolerances, advise on design improvements and always be able to offer expertise for your specific application.

6. Confidentiality and care
If your parts are proprietary, confidentiality and careful handling are essential. Always choose a company that protects your designs and components as if they were their own.

The benefits of sub-contract balancing

Working with a specialist like CEMB Hofmann UK brings several key advantages:

No capital investment
Avoid the cost of purchasing, maintaining, and staffing a balancing machine.

Access to advanced technology
Use the latest, high-precision balancing systems and analysis equipment.

Consistent quality
Every part is balanced to certified standards by experienced technicians.

Reduced downtime
Outsource balancing to maintain production flow while machines are serviced or to meet demand peaks.

Independent verification
Get objective data and certification for customer assurance or compliance purposes.

Nationwide service
We serve customers across the UK, offering quick turnaround and reliable logistics support.

 

We operate one of the most comprehensive sub-contract balancing facilities in the country. 

 

From small precision rotors to large industrial assemblies, we combine decades of expertise with state-of-the-art balancing technology.

 

Our capabilities include:

Our engineers work closely with our clients to understand their operational context and balance requirements, ensuring that every component performs reliably and efficiently once reinstalled.

 

Balancing isn’t just a technical requirement. It’s a vital part of ensuring reliability, efficiency, and longevity in rotating machinery. By choosing the right sub-contract balancing partner, you can reduce risk, improve product quality, and keep your operations running smoothly.

 

Whether you need one-off prototype support, ongoing production balancing, or diagnostic assistance, choose a partner that has the experience, equipment, and expertise to deliver dependable results every time.