Racing certainties

Mills CNC has recently supplied leading precision subcontract specialist SRD Engineering with three new Doosan machining centres. The new investments have taken the machine tool tally to just shy of 40 – a significant quantity of which are Doosans. PES reports. 

The machines, two DNM 4500 (3-axis) vertical machining centres supplied with Nikken 4th-axis units, and a DVF 5000 simultaneous 5-axis machining centre, were installed at the company’s 18,000ft² facility in June 2021.

Since their arrival the new Doosans are being used to machine a range of high-precision and often complex components for customers operating in the F1 and motorsport, automotive, electronics, medical devices, power generation and aerospace sectors amongst others. 

These components are machined in small-to-medium batches and are made from a diverse range of materials that include Inconel, titanium, stainless, steels, aluminium, plastics and nylon.

Typical components machined by SRD are characterised by their tight tolerances – 8 - 10µm on tied up features and exacting surface finish requirements of Ra 0.8um or better. Part cycle times vary considerably – from a few minutes at one end of the spectrum through to over nine hours at the other.

The parts machined by SRD Engineering are also often required in short lead-times, especially where the F1 and motorsport sectors are concerned. This helps explain why the company operates 24/5, and why it is committed to investing in technologies that are designed to improve productivity and efficiency levels.

Mark Bonham who, along with brother Paul, are the directors of the company comments: “We operate in demanding and competitive sectors where quality, lead-time fulfilment and cost competitiveness are the Holy Grail. If you are weak in any of these areas, you’ll be found out quickly.”

About SRD Engineering

SRD Engineering was established in 1989 by Steve Bonham (Mark and Paul’s father), and two other business partners. Despite modest beginnings the company, built on the principles of delivering high-quality and competitively priced machined components to customers on time, every time, thrived. And, despite some bumps along the way, SRD Engineering’s fortunes have been on an upward trajectory.

Over the last 32 years the company has changed dramatically and grown exponentially. Today, it operates from an 18,000ft² facility in Bicester, employs 85 members of staff and has just shy of 40 CNC machine tools at its disposal.

Continuous improvement: Project 24

A constant and recurring theme throughout the company’s 32-year history, is its commitment to continuous improvement and the regular and strategic investments it has made in its people, plant, equipment, processes and systems.

Mark Bonham explains: “To ensure that you are meeting, and hopefully exceeding, customers’ expectations you need to monitor and benchmark your business performance and address any weaknesses or concerns before they can impact on your ability to meet quality, lead-time and cost-down requirements.

“We have systems in place to ensure that this is a priority and our latest continuous improvement programme, Project 24, a company-wide initiative implemented in 2019, focused on Restructuring, Redeployment, Training and Investment. It provided the catalyst and rationale for the recent three Doosan machine tool investment.”

Project 24 helped identify a weakness in SRD’s milling section – specifically with three older vertical machining centres which, owing to their age and through constant use, were becoming more unreliable, required consistent and costly maintenance intervention and, if left unchecked, would create production bottlenecks.

To avoid production pinch points from occurring, the company decided to replace the three older machines with more advanced machine tools and approached the market to identify suitable replacements.

Machine tool investment history and strategy

SRD Engineering has close to 40 CNC machine tools at its disposal. A significant percentage of these are Doosan machine tools supplied by Mills CNC. The majority of the 13 Doosan Lynx and Puma lathes at the company’s facility have sub-spindles, Y-axes and driven tools and its Doosan DNM machining centres have integrated 4th-axis units.

Mark Bonham explains: “We are always looking to increase our machining capabilities and not just our capacity. Multi-tasking and multi-axis machine tools help increase our productivity and operational efficiencies. Being able to machine components in one hit and reduce part cycle times enable us to better meet customer deadlines.

“Furthermore, reducing the number of job set ups required to complete a job and avoiding the need to transfer work from one machine to another ensures that part accuracies and repeatability’s are not compromised.

“Doosan lathes and machining centres are good machines and, from a price/performance perspective, are difficult to beat. The fact that over 50% of the CNC machines we have in our facility are Doosan machines is testament to their consistently high performance and reliability.

“We are similarly impressed with Mills CNC,” he adds. “The company is proactive, knows our business inside-out and has, what we consider to be, industry-leading and best-in-class aftersales service and support.”


The outbreak of the pandemic in March 2020, as was the case with many UK manufacturing companies, had a significant impact on SRD Engineering with orders being postponed and in some being cancelled altogether.

However, the company, through its strong and preferred supplier relationships with several F1 Teams was able to weather the storm by being actively involved in machining high-precision ventilator parts.

“We were in uncharted territory and the ventilator contracts were important to us. They enabled us to keep the doors open and the spindles turning,” Mr Bonham recalls. “The Government’s Coronavirus Business Interruption Loan Scheme (CBILS), introduced in response to the pandemic, also helped keep things moving.

“COVID-19 had affected our ability to roll-out our Project 24 continuous improvement programme, but the introduction of CBILS and its favourable repayment terms and conditions, combined with the upturn in business activity and its positive impact on confidence, enabled us to get our investment plans back on track.

With renewed optimism and determination to capitalise on the economic upturn, SRD Engineering approached the market in 2021 with its new milling machine tool requirements.

The new Doosan machines: DNM 4500

“We approached Mills CNC with our requirements,” says Mr Bonham. “We had previously invested in Doosan DNM machining centres with 4th-axis units some years earlier and, owing to the machines’ reliability and performance, decided to replace two of our older milling machines with two new DNM 4500 machining centres.”

The two machines supplied to SRD are equipped with the latest Fanuc 0iMP control, 12,000rpm directly coupled spindles, integrated thermal compensation, LM roller guideways, 30 tool position quick-change ATCs and Filtermist extraction systems.

To increase the productivity of the machines both were also supplied with Nikken CNC202 rotary tables.

The new Doosan machines: DVF 5000

SRD Engineering is no stranger to 5-axis machining and has a dedicated 5-axis milling section in its facility. “We are keen advocates of 5-axis machining and the way it can dramatically improve company productivity and performance,” Mr Bonham affirms.

“In discussing our future milling requirements and production strategies with Mills CNC’s sales and application engineers, we decided that the third machine we would acquire would be a high-performance, simultaneous 5-axis machining centre capable of processing a range of parts.”

The machine identified was the Doosan DVF 5000 – a compact, simultaneous 5-axis machining centre equipped with a 12,000rpm direct-drive spindle, 60 tool position ATC, linear guides, an efficient swarf conveyor system, Filtermist extraction and the Fanuc 31iB5 control.

“We negotiated a great deal with Mills and part-exchanged our three older machines for the three new ones. All three machines were delivered and installed at our facility in June 2021.”

Going the extra mile

Key strengths and market differentiators that help separate SRD Engineering from other precision subcontractors are its commitment and ability to go the extra mile for customers, and its laser focus on growth and improvement.

In recent years the application of both have seen the company:

  • Invest in sliding head technology enabling it to machine high-precision, complex components in large volumes for its customers. From a standing start the company now has four sliding head lathes at its disposal
  • Significantly improve its inspection and measurement capabilities. The recently implemented Project 24 initiative identified the need to further upgrade its capabilities by investing in another CMM and making its inspection room fully air conditioned
  • Stock heat treated materials at its facility just in case a specific F1 customer needed components to be machined and delivered immediately. This proved to be the case
  • Bring many machining processes in-house. To ensure quality, cost competitiveness and lead-time fulfilment, SRD has lessened its reliance on outside subcontractors – preferring to bring several secondary services and specialisms in house

SRD Engineering

Mills CNC


Mills CNC [**]

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