European Society for Precision Engineering and Nanotechnology

Euspen Logo

The European Society for Precision Engineering and Nanotechnology or Euspen was founded to bring together industrialists, academics, researchers and industry bodies to form a cohesive and influential organisation representing the precision engineering community as a whole.

Furthermore, the community serves as a great networking platform and nurtures entrepreneurial spirit. Euspen is at the forefront of precision engineering and serves as a great arena to share and learn about new technology and industry trends. 

Euspen was formed in 1999 and is headquartered at Cranfield University, a central pillar of the precision engineering community.

Cranfield Precision is a Euspen Corporate Sponsor and helps to promote Euspen activities and support the precision engineering community.

What is Precision Engineering?

Precision Components

This seems like such a simple question yet it is often blurred or confused by various quotes and uses of the term precision.


Broadly speaking, the classic definition of Precision Engineering is an accuracy of 1x10-6 which is one part in one million or 1 micron in 1 metre. This is increased ten fold to 1x10-7 to determine that the level of accuracy falls under the realm of Ultra Precision Engineering.


These definitions in them selves do not mean very much though. These rather broad definitions really just apply to plain dimensional measurements such as the length of a component. These can still be perfectly valid in a precision engineering process, however they are seldom the only categorisation or precision engineering.


More specific definitions of precision that consider aspect ratio or form accuracy are often more useful and valid as a means of stating that something is precision engineered. For example, there are many small so called precision engineering machine shops that do not use temperature control and struggle to achieve tolerances of even a few microns over 100mm or less. This would not be considered precision engineering. Then there are more modern examples such as micro-machining which also can't achieve the 1x10-6 definition of precision but are accepted as precision engineered components due to their very small size and physical challenges of producing a certain aspect ratio.

Machine Tool Error Compensation

Machine Tool Error Motions

A major part of a precision machine tool system is its control system, and more importantly the ability to apply error compensation. With a stiff and repeatable base mechanical system, high resolution transducers and the application of precision metrology it is possible to accurately correct the errors in a machine tool system to give significantly reduced error motions.

By calculation of measured error motions and accurate measurements it is possible to correct for a large number of geometric and dynamic error motions that can occur in a machine tool system.

Accurate machine tool metrology and error compensation is what turns a good machine tool into an excellent machine tool. Cranfield Precision has vast experience in machine tool metrology and in the application of advanced error compensation techniques. This is made possible through our advanced CNC control system, allowing for complex error motions to be effectively compensated.

CNC6400 - Advanced CNC Control System

CNC 6400 Control System

The CNC 6400 Control System is Cranfield Precision's flagship CNC Control System.

Cranfield Precision has a history of producing advanced control system technology and was the first to control company to create a camshaft following profile to produce a master cam revolutionizing the automotive industry.


Cranfield Precision's EGB (Electronic Gear Box) allowed for the precise synchronization of multiple machine axes allowing complex motions to be produced very accurately.


There are numerous advantages of having a precision machine tool company with their own CNC control system software rather than using 3rd party vendor control systems. With an in-house software team it is possible to quickly and effectively tailor the control system to meet specific machine and process requirements.


Today Cranfield Precision employs advanced control system techniques and uses modern control hardware capable of producing some very complex and accurate machine tool motions.

Cranfield Precision are at the 26th Annual Meeting of the American Society for Precision Engineering (ASPE)

The 26th Annual Meeting of the American Society for Precision Engineering is happening between Sunday and Friday the 13th to the 18th of November 2011 at the Denver Marriott City Center Hotel, Denver, CO, USA.

Cranfield Precision is attending the conference and will be represented by Mark Stocker, division manager.

Come and talk to us about your complex manufacturing challenge or general precision engineering related topic.

Visit our web site to learn more about Cranfield Precision - www.cranfieldprecision.com

The DT40 High Precision Lathe

DT40 - High Precision Lathe

The Cranfield Precision DT40 (DeltaTurn 40) is a high precision lathe comprising a unique machine cell design allowing it to be very compact, stiff and stable.

The DT40 produces high accuracy hard turned components and has been used for automotive, electronic and aerospace parts.

Read an in-depth technical case study on the design and development of this high precision lathe.

High Precision Hard Turning

Kodak OAGM 2500 Off Axis Grinding Machine

Kodak OAGM 2500 - Off Axis Grinding Machine

The Kodak OAGM 2500 Off Axis Grinding Machine is a classic example of a special purpose machine.

This machine was built in a specially made facility in the UK for proving and acceptance testing before being shipped to the USA.

Read a case study on the Off Axis Grinding Machine here.

Machine concept

The initial concept of the OAGM 2500 machine shows how Cranfield Precision take a manufacturing problem, create a concept and a design and then turn it into a special purpose machine tool.

Machine Assembly

Assembly of the large machine structure shows the symmetry and nature of the stiff repeatable structure.

Ensuring the surfaces are correctly formed and alignments are correct is a key part of the highly skilled assembly process.

Mirror Segment Inspection

Technicians inspect the mirror segments that are manufactured in a controlled facility on the OAGM 2500 in Kodak's production facility.

High Precision Horizontal Boring Machine

High Precision Boring Machine

Cranfield Precision has produced a high precision horizontal boring machine. The machine was designed and developed to meet a need for our parent company Cinetic Landis Ltd where there was no commercially available machine that could achieve the required accuracy over the 4m³ work volume.

The machine is designed as a high accuracy finish jig boring machine capable of multi-purpose machining functions such as; mill, drill, ream, face and bore in one set-up

Read a case study on the design and development of the high precision boring machine here.

Initial 3D CAD Concept

The Principle of Determinism

Precision Machine Tool

Precision Machine Design adheres to the fundamental principle of determinism. The principle of determinism is that machine systems obeys cause and effect relationships. The principle of determinism does not accept the word random, it suggests that nothing is random and at some level there is a cause for the observed effect.

The repeatability of a machine tool is not driven by some inherent and seemingly random limiting process. With the ability to measure all of the influencing variables we can aim to better control them and therefore produce a more accurate machine tool.

Layton Hale's PhD Thesis (10mb PDF) talks about the principles of determinism and that the list of variables that cause errors in machine tools is not so long that we can't control them.

Cranfield Precision has a proven track record of producing highly accurate precision machine tools that are designed and produced using deterministic techniques.

Repeatability in Precision Machine Tools

Repeatable Machine Structure

Repeatability is one of the most important elements in precision machine tool design. The aim is to make a mechanical structure that is stiff and repeatable. Having a stable and stiff mechanical structure is the basis for a high precision machine tool.

Finite Element Analysis
of a machine element

At Cranfield Precision we design high precision machine tools with stiff and repeatable structures through advanced finite element analysis techniques and by obeying the key principles of precision machine design.


Once you have a stiff and repeatable mechanical system that will consistently repeat to a demanded position advanced control system and error compensation techniques can be applied to correct any measured errors. 


Precision metrology techniques are used to accurately measure machine error motions. The combination of a stiff repeatable structure, precision metrology and error compensation techniques produces a very accurate precision machine tool.

Error Budgets and Error Budgeting Techniques

An error budget is a method employed in ultra precision machine design that identifies the accuracies of individual machine elements and gives a useful value as to the over all machine accuracy. This technique can identify potential weak spots in a machine concept and be used to focus design effort into ensuring that every element of a machine tool is fully optimised.

6 degrees of freedom for a machine tool axis

Each machine element will have a potential error motion or influence in 6 degrees of freedom dependent on  the constraints in place.

Error budgets are used with a good deal of experience and where necessary previous results and test beds to prove a principle or concept.

Read more on error budgeting techniques here.

The 11 Principles of Precision Machine Design

The 11 Principles of Precision Machine Design

The 11 Principles of Precision Machine Design were developed at CUPE - Cranfield Unit for Precision Engineering which ultimately evolved into Cranfield Precision. Development of the 11 Principles of Precision Machine Design and CUPE were lead by Professor Pat McKeown.

Cranfield Precision are world renowned for their expertise in designing and developing special purpose machines. Many new and existing world leading precision machine tools are still based on the 11 Principles of Machine Design which Cranfield Precision still utilise today.

The 11 Principles of Precision Machine Design

• 1. Structure
• 2. Kinematic / Semi Kinematic Design
• 3. Abbe Principle
• 4. Direct Displacement Transducers
• 5. Metrology Frames
• 6. Bearings
• 7. Drives / Carriages
• 8. Thermal Effects
• 9. Servo-Drives and Control (CNC)
• 10. Error Budgeting
• 11. Error Compensation

Cranfield Precision has developed and improved upon each of these key principles and has also developed many new technologies that embody and advance these principles.

Read more on the 11 Principles of Precision Machine Design.

Precision Machine Design

Cranfield Precision are specialists in Precision Machine Design. Cranfield Precision has a rich history of designing precision machines, born out of Cranfield University's Unit for Precision Engineering we fully embody the 11 principles of precision machine design as defined by Prof Pat Mckeown (former MD Cranfield Precision).

• Precision Machine Design
• 11 Principles of Precision Machine Design
• Error Budgeting

 Cranfield Precision has an extensive history in producing world beating precision machine tools dating back to 1968. The company was born out of Cranfield University's Unit for Precision Engineering and still has ties with the University and plays a central part in the Precision Engineering Industry.

Read more at www.cranfieldprecision.com