Micro torsion spring for medical application


A prominent medical device company specialising in minimally invasive surgical equipment approached CBS with a unique requirement for a micro torsion spring made from 0.15mm wire.

The client's innovative surgical device aimed to improve precision and flexibility during delicate procedures, requiring a highly specialized spring component to facilitate its functionality.


The project posed significant challenges due to the miniature scale and intricate design specifications of the micro torsion spring. Among these challenges were the need for miniaturisation to fit within the compact dimensions of the medical device without compromising performance, the requirement for precision engineering to ensure precise torsional characteristics for optimal functionality and reliability during surgical procedures, and the necessity for biocompatibility in the material used for the spring to ensure patient safety and regulatory compliance within the medical industry.

Technical Approach:

To address the client's requirements, CBS embarked on a comprehensive technical approach:

  • Custom Design: Our team of engineers collaborated closely with the client to understand the specific requirements and performance criteria of the micro torsion spring. Utilising advanced CAD software and simulation tools, we developed a custom design optimised for the application.
  • Material Selection: After thorough research and testing, we selected a biocompatible material that met the stringent regulatory standards of the medical industry while ensuring the necessary mechanical properties for torsional performance.
  • Precision Manufacturing: Leveraging our state-of-the-art manufacturing facilities and advanced machining capabilities, we meticulously produced the micro torsion spring with utmost precision and accuracy, adhering to tight tolerances and quality standards.
  • Testing and Validation: Prior to final delivery, the springs underwent rigorous testing and validation procedures to ensure they met the client's performance requirements and complied with regulatory standards for medical devices.


The collaboration between CBS and the medical device company resulted in the successful development and production of the micro torsion spring. Key outcomes included:

  • Miniaturisation: Despite the challenges posed by the small size, CBS engineered a micro torsion spring that met the client's size constraints without sacrificing performance.
  • Precision and Reliability: The springs exhibited precise torsional characteristics, providing the necessary flexibility and control required for the surgical device's functionality.
  • Regulatory Compliance: The selected biocompatible material ensured the springs met the regulatory requirements for medical devices, contributing to the safety and reliability of the overall product.
  • Customer Satisfaction: The client expressed satisfaction with the quality, performance, and timely delivery of the micro torsion springs, highlighting CBS's ability to meet their exacting standards and exceed expectations.


The successful development of the micro torsion spring exemplifies CBS's technical expertise, precision engineering capabilities, and commitment to delivering tailored solutions for the medical industry. Through collaborative partnership and innovative thinking, CBS continues to support advancements in medical technology by providing high-quality spring components that meet the unique needs of our clients.

Clock Spring for Aerospace Application


In collaboration with a leading aerospace company, CBS undertook the development and production of a specialized clock spring for critical aerospace applications. This case study highlights our technical expertise, precision engineering, and commitment to meeting the stringent requirements of the aerospace industry.


The aerospace company required a highly reliable clock spring to be used in the actuation mechanism of a cutting-edge aerospace system. The spring needed to withstand extreme temperatures, operate flawlessly under high stress conditions, and maintain precise tension and torque levels throughout its lifespan. Additionally, strict adherence to aerospace quality standards and regulations was imperative to ensure safety and reliability in flight operations.

Technical Approach:

Drawing on our extensive experience in spring manufacturing and aerospace engineering, CBS's team of experts embarked on a comprehensive analysis of the project requirements. We conducted thorough research into suitable materials and manufacturing techniques to meet the demanding specifications and tolerances of the clock spring.

Utilising advanced design software and simulation tools, we engineered a bespoke clock spring tailored to the precise needs of the aerospace system. Our design incorporated innovative features to enhance durability, minimise weight, and optimise performance in the aerospace environment. Additionally, we implemented rigorous quality control measures throughout the manufacturing process to ensure compliance with aerospace industry standards and regulations.


The clock spring developed by CBS exceeded the expectations of our aerospace client in terms of performance, reliability, and quality. Rigorous testing confirmed the spring's ability to withstand extreme temperatures, maintain precise tension, and operate flawlessly under high stress conditions, meeting the stringent requirements of aerospace.

Custom Compression Spring for Oil and Gas industryBackground:

In the demanding environment of the Oil & Gas industry, equipment reliability is paramount. A leading oil and gas company approached CBS with a unique challenge: they required a highly durable and corrosion-resistant compression spring to withstand extreme conditions in their drilling operations. With rigorous performance requirements and tight deadlines, CBS was tasked with delivering a custom solution that would ensure optimal performance and longevity in the field.

Technical Approach:

CBS began by conducting a thorough analysis of the client's specifications and operational requirements. Understanding the critical nature of the application, our team of engineers meticulously designed the compression spring to meet the highest standards of performance and reliability. Leveraging our expertise in materials science and advanced manufacturing techniques, we selected corrosion-resistant materials and employed precision machining processes to ensure the spring's durability and longevity in harsh operating environments.

Custom Solution:

The custom 14mm compression spring developed by CBS featured:

  • Corrosion Resistance: Utilising high-grade corrosion-resistant materials, including stainless steel or corrosion-resistant alloys, to withstand exposure to harsh chemicals and environmental conditions commonly found in Oil & Gas drilling operations.
  • High Load Capacity: Engineered to withstand high loads and pressures encountered during drilling operations, ensuring reliable performance and longevity in the field.
  • Precision Engineering: Manufactured to exact specifications with tight tolerances to guarantee optimal fit and function within the client's equipment, minimising downtime and maintenance costs.
  • Extended Service Life: Designed for maximum durability and resilience, the compression spring offered an extended service life, reducing the need for frequent replacements and enhancing overall operational efficiency.


The custom 14mm compression spring developed by CBS exceeded the client's expectations in terms of performance, reliability, and durability. Upon implementation, the spring demonstrated exceptional resilience in the harsh operating conditions of Oil & Gas drilling operations, contributing to improved equipment reliability and reduced downtime. The client praised CBS for delivering a tailored solution that addressed their specific needs and requirements, solidifying our reputation as a trusted partner in the Oil & Gas industry.


Through close collaboration, technical expertise, and unwavering dedication to quality, CBS delivered a superior clock Through our technical expertise, precision engineering, and commitment to customer satisfaction, CBS successfully delivered a custom 14mm compression spring that met the rigorous demands of the Oil & Gas industry. With a focus on quality, reliability, and performance, we continue to support our clients in achieving their operational goals and driving innovation in their respective markets.

Extension Spring for Automotive applicationBackground:

In the dynamic automotive industry, precision and reliability are essential elements for vehicle performance. A prominent automotive company approached CBS with a critical need, to develop a custom extension spring for a vital component in their vehicle suspension system. The extension spring had to meet rigorous performance standards while enduring the demanding conditions of daily driving. CBS, renowned for excellence in spring manufacturing, was entrusted with delivering a solution to enhance vehicle performance and reliability.


The challenge lay in engineering an extension spring that could withstand the forces and loads inherent in vehicle suspension systems. The spring needed to maintain its integrity and performance over prolonged periods of use, enduring various driving conditions without compromise. Meeting these criteria required careful consideration of material selection, design optimisation, and manufacturing precision.

Technical Approach:

CBS initiated the project by closely collaborating with the automotive company's engineering team to understand precise specifications and performance criteria. Utilising advanced materials and cutting-edge manufacturing techniques, CBS engineers employed finite element analysis to optimise the spring's geometry and configuration. High-tensile strength materials were chosen to ensure durability, while precision manufacturing processes guaranteed consistency and reliability in every unit produced. Additionally, surface treatments and coatings were applied to enhance corrosion resistance, prolonging the spring's service life and maintaining performance under harsh environmental conditions.


Upon implementation, the custom extension spring exceeded expectations for performance, reliability, and durability. Rigorous testing and validation confirmed its ability to meet and surpass industry standards for automotive applications. Seamlessly integrating into the vehicle suspension system, the extension spring contributed to improved ride comfort, stability, and overall driving experience.


Through technical expertise, precision engineering, and commitment to quality, CBS delivered a custom extension spring that met the rigorous demands of the automotive industry. This collaboration exemplified CBS's dedication to providing innovative solutions that drive performance and reliability in vehicle design. As a trusted partner in automotive spring manufacturing, CBS continues to support clients in achieving their goals and pushing the boundaries of automotive

Case Study

Sector: Musical Instrument Restoration

Type of part: 380 year old Harp Spring

Production Type: Small Volume Custom Clock Spring

Customer Requirement:

A restorer of old musical instruments was finding it incredibly difficult to find a manufacturer interested enough to help produce small volume clock springs. A 380 year old Harp needed this part to complete its restoration.

Engineering Solution:

We understand that not every job will lead to mass volume production and that sometimes, showing an interest can lead to learning and in this case, lead to a Classical Harp being back in its collection and working as it should.

Production Solution:

We're proud to be offer the same level of engineering for all our customers. Whether its a multi-national business or a craftsman in need of some expertise, we are happy to help.

Current State: Harp is back in its collection and working as it should!

Case Study

Sector: Plastics Moulding

Type of part: 5m Auger Screw

Production Type: One off conveyor machine part

Customer Requirement:

A local plastic moulding business had production shutdown after their conveyor system went down. The part required would take weeks to arrive from the manufacturer and that meant a closed production line.

Engineering Solution:

After an initial discussion CBS analysed the broken part, an auger screw. We identified and sized up the required material and ordered in stock. We then set up the tooling to replicate the 5m screw.

Production Solution:

Within days, the conveyor system was back up and running and the customer could get back to production. Taking a 3 week loss of production and reducing it to one.

Current State: Conveyor System up and running with 2 weeks production time saved

Case Study

Sector: UK Hydraulic & Valve Manufacturer

Number of parts: 100+

Product Type: Compression Spring

Delivery Type: Just in Time (JIT) / No customer stockholding / Short Lead times

Customer Requirement:

A leading UK Hydraulics Manufacturer contacted CBS to quote for a large compression spring package, with short lead times and no customer stock holding.


At the CBS Facility, the team set up production cells that produce the various compression spring part range accurately and quickly.

Working closely with the customer, the CBS Teams then set up the communications and process for production and Just in Time delivery.

Current State: CBS Vans deliver parts 2-3 times a week precisely when the production team needs them.

Case Study

Sector: Medical Equipment Manufacture

Type of part: Small Compression Spring

Production Type: Part Production & Clean Room Assembly

Customer Requirement:

The current assembly was not operating as required on a safety blood device. A small compression spring seemed to be the issue. They contacted CBS to see if we could help.

Engineering Solution:

Our engineering team analysed the spring and the assembly, to better understand the operational requirements the spring needed to meet. Using a cross section and modelling, we were able re-design the spring and reduce the tensile strength of the wire giving perfect results.

Production Solution:

Due to the very small compression spring part, delivering in bulk often causes tangling and this was slowing production down for the customer. CBS offered an assembly solution that improved production by assembling the unit in a clean room environment, straight off the coiling machine. The completed assembled parts are then delivered to the production facility. This also meant that we could omit heat treatment from the process, increasing production.

Current State: Delivering assembled units to customer exactly when required.

compression spring iconCOMPRESSION SPRING OVERVIEW

Compression Springs are the most common coiled spring, used in countless products from pens to valves and beyond. In order for CBS to create a bespoke design that is specific to your application, Central Birmingham Springs employ modern and traditional methods, utilising the correct materials and process to produce that perfect fit to your specific solution.

Compression springs are the most popular types of springs. Compression springs work by resisting compression forces and keeping energy in the push mode. While all compression springs work using the same principle, the principle is applied in different ways. These include nonlinear load deflection, extreme space efficiency, and a better energy storage capacity.

Compression springs are open-coil springs, suitable for linear applications. When the spring is compressed the force created will push the spring back to its open position. Different configurations of coiling, material and treatment give unique characteristics to the spring, allowing it to work precisely within many applications.


  • Valves (domestic and industrial applications)
  • Electronics (push button / switch)
  • Manufacturing machinery
  • Industrial Clutch and Brake applications
  • Power Switches

For more information on our manufacturing process and to get in Contact - click here.

What is a constant force spring?

A constant force spring, also known as clock spring, is typically a roll of pre-stressed strip that can exert a mostly constant force to withstand uncoiling. This is achieved because the changes in the curvature’s radius are also constant. However, the force is just truly constant when this variation is disregarded.
Constance force springs are generally designed as a rolled ribbon of steel spring which is quite similar to a rolled-up unit when relaxed. Due to their virtual absence of inter-coil friction, constant torque, and long-extension capabilities, many designers have used them in many industrial applications which require a counterbalance against heavy-moving components such as motors or van doors.

Operation of constant force springs

A constant force spring can be tightly mounted with the terminal attached to its load force and interior layers which are coiled around itself. The interior diameter might be tied to a moving drum. During operation, the resistance is generated by the spring's effort to return to the natural, wound state. The thickness and width of the material, the drum’s diameter, and natural radius curvature all determine its extension resistance. Once the spring has been extended to 1.25 times the diameter, it will achieve a full- load rate and easily reach the loading capacity.

Technical features of constant force springs

When choosing constant force springs, keep in mind the following technical features:

Constant force springs are mostly constructed from 301 stainless steel due to its durability and low cost. It is able to attain ductility and highly tensile strength in cold working conditions. In addition, Inconel and high-carbon steel are other common materials.
The drum attracted to the interior diameter is often made of plastic, which provides coil attachment, structural integrity, as well as reduce friction compared to a metal unit.

Estimated life cycles
The life of constant force springs isn’t time-dependent. Instead, it can be determined by the relation between the material’s thickness and its diameter. A higher estimate makes the unit bigger and more expensive, but these units can also last longer.

Required force
The force of the springs should be equal to the application’s requirements. Basically, the usual tolerant should be approximately 10%.

Available space
There are a few combinations of material width and thickness which could be applied for any force values. The natural diameter of the coil will depend on the force, life, and thickness required.

Mounting methods
There is a variety of mounting options for constant force springs. These include single, dual, front-to-front dual, back-to-back dual, and back-to-back dual-dual

Common applications
As said earlier, this type of spring is applied in many industries thanks to its constant torque and long-extension capabilities. Some of the applications include door closers, hose retrievers, cable retractors, counterbalances, space vehicles, appliances, electric motors, toys, hair dryers, gym equipment, furniture & cabinet components, and other devices which require constant loads. Also, you can find these units in retail beverage racks to deliver products to the cooler door.


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    Central Birmingham Springs Limited
    Unit 7D. Waterfall Lane Trading Estate
    Waterfall Lane. Cradley Heath
    T: 0121 248 1112
    E: [email protected]
    Company No. 04256582