It’s always good to have choices. If you own a coordinate measuring machine (CMM) and are looking for an independent UKAS (United Kingdom Accreditation Service) accredited company to service, maintain and calibrate it, Bedford-based N J Metrology should be on your shortlist. Dave Tudor reports.
N J Metrology is a family business located in Bedford and headed up by managing director Neil Marriott. When it comes to metrology equipment, the company can take care of all your calibration and servicing needs for just about anything.
Representing around 70% of its workload however, CMMs are the main area of expertise. N J offers fully traceable, sub-micron uncertainty on CMM calibration and error mapping – but the service/calibration aspect of the business also extends to articulated arms, laser scanners, surface tables, profile projectors and height gauges. Repairs, retrofits, breakdown support and training complete the extensive service portfolio on offer, which incorporates hardware, software and programming.
Moving your CMM from one part of the factory to another or even to different premises altogether? Well, it’ll definitely need re-calibrating afterwards. You may have also knocked an encoder out of whack en route so this will likely need resetting with an oscilloscope or even replacing.
From this to things like renewing degraded air pipes, servicing the CMM from top to bottom, cleaning and replacing defective or failing parts and attending to breakdowns – these are all common scenarios and tasks that N J undertakes on a regular basis.
Similarly, retrofits can breathe a new lease of life into an aging CMM. N J can replace parts like scales and controllers and also, where possible, install new, modern software and operating systems.
UKAS – setting the standard
Neil Marriott has worked in the metrology field for more than 40 years with much of that vast experience centred around CMMs. He set up N J Metrology in 1998, started the ISO 17025 approval process in 2003 and gained full accreditation in 2005. The company is also accredited to the International standard ISO 10360 for CMM verifications.
To clarify, ISO 17025 is a nationally and internationally recognised standard for testing and calibration laboratories. For N J’s customers – existing and prospective – it demonstrates credibility and reliability in terms of its testing, measurement and calibration processes. More fundamentally, it assures commitment to an established quality system.
Whereas ISO 17025 is generic and all-encompassing, ISO 10360-2 specifically addresses the acceptance tests for verifying the performance of CMMs. The former effectively provides the structured framework for the latter.
“I believe a true differentiator for us in the marketplace is our UKAS accreditation,” Neil Marriott affirms. “It is the gold standard and we’re regularly audited. For example, we have a number of customers that operate in a variety of demanding sectors such as automotive and for their particular applications, having a UKAS label on their CMMs and surface tables is mandatory.
“All the artifacts that I use to calibrate my customers’ equipment are UKAS calibrated, but not only that, we – the staff – have to be as well. Both my son Adam, who works in the business, and me are assessed regularly by UKAS to ensure we’re suitably qualified and trained to carry out the work we do.”
UKAS is the National Accreditation Body for the UK. Its purpose in life is to assess, audit and accredit organisations – like N J Metrology – that provide certification, testing, inspection and calibration services.
Gaining UKAS accreditation is not only expensive, but very stringent and exacting. It’s effectively a quality system that takes in things like training records and matrixes for staff, and precise plans for nonconforming products. All of N J’s reference equipment is audited annually, and every time the company issues a UKAS certificate for a piece of equipment on behalf of a customer, it needs to be verified by UKAS.
Not for the faint hearted certainly but for quality assurance purposes, it adds an extra layer of reassurance for the customer that things are being done properly. Definitely money well spent in N J’s case.
It’s all about temperature
N J Metrology offers full UKAS calibration for CMMs and surface tables, and a traceable calibration of articulated arms, laser trackers, optical VMMs (vison measuring machines) and laser scanners.
Not surprisingly, because CMM servicing and calibration services are typically carried out on an annual basis, often via a service contract agreement, much of N J Metrology’s work is field-based at customer sites.
But the company also makes effective use of an air-conditioned (held at a constant 20°C) lab which doubles up as both an office and a facility for calibrating and servicing the more portable pieces of equipment that can be easily transported.
“Accurate measurement is all about controlling temperature,” Mr Marriott explains. “With master measuring bars a 1°C ambient temperature deviation from, say, 20 to 21° can result in 11µm of expansion in length so when we’re visiting customers to carry out a calibration on a CMM, this has to be factored into our processes.
“Master measuring bars must be kept at a constant 20°C which is why we have an air-conditioned lab. When we leave for a customer visit in the morning, the masters go straight from our lab into a van and are never exposed to temperature fluctuations.
“When we arrive on site, we use highly accurate thermistors to check both the measuring bar and the air temperature. They must be within 1°C of each other before we even start a calibration process on a CMM.
“Typically, we can complete a CMM calibration within a day, but it can spill over into two if there are temperature deviations that need to be stabilised. We always try to optimise visits – if we’re calibrating a CMM and the customer also has a profile projector, a surface table or a height gauge for example, we’ll aim to calibrate those as well at the same time. We can even hand lap surface tables as part of a refurbishment process.”
Certainly worthy of note is the fact that Mr Marriott is a BSI committee member, the benefits of which are essentially twofold: it gives him the opportunity to shape future policy; and ensures he’s up to speed with new developments and technology in the metrology arena.
The virtues of independence
Being unbiased and impartial in any walk of life has its advantages, and this is clearly a quality that has underpinned N J Metrology’s success since its formation.
“Because we’re 100% independent, we have experience of working with all the major brands of CMM,” Neil Marriott concludes. “It’s all about the total service package we can offer. For example, with an aging machine that has broken down and spare parts are obsolete, we can often source the part ourselves, provide an equivalent alternative or repair the part to get it up and running again.
“Once we’ve helped a customer on a breakdown for example, chances are they’ll take out a servicing and maintenance contract with us if they don’t have one already. Because our overheads are low, we can keep costs down and as a small family business, we really do value our customers and offer a personal service with rapid response times.
“I strongly believe these are our USPs in the marketplace – and we’re very busy. We’re calibrating and servicing around 30 machines a month and that’s just CMMs. The fact we get a lot of repeat business and customer recommendations means we’re clearly doing something right!”
N J Metrology
www.njmetrology.com
