Quality first

18 March 2010



During tough economic times it is tempting to reduce quality control to cut costs. However, Dolph Beyer, an engineer with Mohawk Fine Papers, asserts that doing this is actually counter-productive.


Recognised for its technical innovation and environmental focus, Mohawk Fine Papers is the largest privately-held premium paper manufacturer in North America. The company says it is firmly of the opinion that cutting costs by cutting quality control is not cost effective.

One of the measures it has taken to maintain quality control is to use Pressurex sensor film from Sensor Products to extend roll life, maximise yields, and improve quality. This, says Dolph Beyer, actually decreases costs while significantly improving product quality.

“By taking nip impressions with pressure indicating film every couple of weeks we have extended roll life by a few months in many cases,” says Mr. Beyer. ”This quality control measure not only lowers costs for the replacement of these covers, but also minimises equipment downtime.”

Pressurex reveals pressure from 0.14 - 3,000kg/cm2

When placed between contacting rollers, the sensor film instantaneously and permanently changes colour directly proportional to the actual pressure applied. Precise pressure magnitude is then easily determined, it is claimed, by comparing colour variation results to a colour correlation chart (conceptually similar to interpreting Litmus paper).

According to Sensor Products, variations in pressure that lead to defects in papermaking, converting and printing can be quickly and accurately detected and corrected - improving yield, decreasing scrap, and increasing productivity.

By examining pressure variations in the nip, corrections in alignment and crown profiles can be made. The film is effective on virtually all roller compositions and surfaces. A visual pressure mapping profile of an engraved pattern or drilled roll can be ‘effortlessly’ produced that exposes minute surface defects and other imperfections.

Pressure indicating sensor film is cited by Mr Beyer as being especially helpful with calendar rolls, which are swim rolls that have mechanisms to allow the centre of the rollers to exert a different level of pressure.

“Similar to crown rolls, swim rolls need to be carefully monitored to ensure even and exacting pressure is being applied to achieve optimum nip conditions,” says Mr. Beyer. “We use the film to create just the right nip and improve the roll shape and crown to deliver better sheet uniformity.”

Mohawk Fine Papers uses Pressurex to take static nip impressions on its press section and dynamic nip impressions on the calendars. Dynamic nip impressions are inspected for uniformity, and static nip impressions for uniformity and nip pressure. The image results from Pressurex are archived and used as a control to compare tools and processes.

Pressurex film is extremely thin (4-8mil) and flexible, which allows it to conform to curved surfaces. It is claimed to be ideal for invasive intolerant environments and tight spaces not accessible to conventional electronic transducers. While recommended for tests in non-operating conditions, the sensor film can be used at temperatures exceeding 93oC for brief intervals.

Headquartered in New Jersey and established in 1990, Sensor Products is a said to be world leader in the manufacture and distribution of tactile pressure sensing solutions. Its customised and off-the-shelf products are installed within all of the Fortune 500 industrial companies, as well as thousands of smaller manufacturing firms. The company’s sensors are used in applications as diverse as tyre testing to semiconductor manufacturing, and from R&D labs to space missions.

Additionally, Sensor Products provides in-house and on-site stress and pressure mapping analysis, as well as a variety of regional technical seminars.

For a free sample of Pressurex in your desired range, contact Sensor Products Inc on +1 973 884 1755 (USA), or email info@sensorprod.com


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