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Digitalisation solves a daily headache for IKO

06 February 2023

SICK helped IKO Roofing digitalise its production speed data using a new laser-based non-contact measurement technology, explains Darren Pratt

THERE are times when the continuous output of just one accurate, digital measurement can transform a manufacturer's ability to control a production process. For IKO Roofing, digitalising production speed data using a new laser-based non-contact measurement technology, solved a daily headache for operating engineers at one of its UK plants, while helping managers thousands of miles away to monitor output, costs and product quality. 

The manufacture of roofing felt is a well-established process that has changed little for many decades. The production machine at IKO's Appley Bridge site in the Lancashire town of Wigan has been producing a bituminous roofing felt to a variety of grades and specifications for more than 40 years. 

Bituminous roofing felt process

Whether the end product is destined for a skyscraper office-block or a garden shed, producing the roofing felt follows the same manufacturing principles: On the 30 metre-long machine, bitumen is applied at 170° C to a 1.0 metre-wide carrier base layer, before minerals and other materials are added according to closely-guarded recipes in a continuous process. 

To enable a continuous length of roofing felt to be manufactured, each time a new roll of base layer is needed, it is spliced to the end of the previous roll and an accumulator mechanism is used as a buffer to ensure the manufacturing process continues at the same speed. 

Once the specified minerals have been applied to the membrane, a series of cylinders gradually cool the product before the final material is wound onto a roll for onward distribution or further manufacture. Higher grade products are produced at lower speeds, while economy products will be output at faster speeds up to a maximum of 75 metres per minute.  

In the continuous production process, one measurement is more important than any other: The speed of the line controls how much material is applied and therefore directly corresponds to how closely the final product has kept to the product recipe. The closer this speed remains to the target, known as 100%, the better the product quality. 

Close tolerances

Keeping the line speed within close tolerances also optimises production output and allows for accurate management of the Bill of Materials.

For operating engineers working on the production line at Appley Bridge, optimising the machine speed is done from the control desk. Guided by a digital counter display located above them, experienced operators use their judgement to speed up or slow down the line and constantly monitor it to keep it within close tolerances during the continuous process. Even a difference of a few metres per minute could lead to inefficiencies in production and use of materials.

But, the engineers had a problem: The digital counter output took its speed measurement from a proximity sensor aligned to a gear mechanism near the beginning of the process. However, line speed data was fed into the company’s PRODAC global MES (Manufacturing Execution System) from an encoder measurement positioned on the winder at the end of the machine.

As a result, different sources of speed data were used by UK operators and managers both in the UK and at the company’s HQ in Canada, resulting in seeing readings that regularly showed a discrepancy. An impact was that, operators could be chasing an unreachable target to hit the 100% speed and quality target, as they responded to feedback from senior management.

Measuring product speed without touching 

"Searching for a new method to measure the production speed was not straightforward, and operating staff spent more than two years looking for a suitable solution," said engineering manager Paul Hayward.

"To get an accurate measurement we want to measure the speed of the product, rather than the speed of the machine, which does not take account of product slippage. Using a sensor like a measuring wheel encoder that is in direct contact with the product is problematic for a material like roofing felt, that could be hot or sticky near the beginning of the process and would also be subject to significant wear.

"We also wanted to move away from measurement devices that have to be integrated into the machine. They can become encrusted in dirt from the process and difficult to access for maintenance or replacement. 

"SICK has worked closely with our Appley Bridge site for many years, so when the SICK representative came to us with news of a new technology that could offer a non-contact, digital solution, we were keen to find out more," he added.

Non-contact laser sensor

The SICK Speetec is a non-contact surface laser sensor for speed and length measurement. Compact, affordable and eye-safe laser, the Speetec offers a solution for a wide range of continuous, web-fed processes or measurement of cut sections with a resolution down to 4 µm, so is particularly useful for manufacturers of building materials. The Speetec's combination of affordability and precision was an attractive option to IKO and SICK support staff worked closely with the Wigan engineering team to install the product.

The Speetec's rugged aluminium housing measures just 140mm x 95mm x 32.5mm and is ideal for the operating conditions at the Wigan plant. The Speetec was set up and integrated directly into the machine’s Allen Bradley PLC, without any additional electronic device being necessary to process the signal output. The measurement is automatically converted onboard the sensor into TTL/HTL signals identical to those of an incremental encoder, so that they can be easily integrated into the machine control system. 

The Speetec's digital output was integrated with both the visual speed counter and IKO’s PRODAC MES system, where it is used to output measurements on the production floor, as well as being accessed remotely by the international management team.

"The SICK support engineers were extremely helpful in providing back-up and technical help to install the product," Hayward continued. "Although the Speetec sensor may be quite sophisticated, the actual output isn’t complicated. It’s doing the clever stuff within the sensor and we are getting simple information out of it.

"Now at our daily engineering meetings, and in our communications with the IKO HQ, we can be confident of accurate digital data," he stated.

A rapid ROI

The Speetec uses the Laser Doppler measurement principle - similar to the doppler effect we are more familiar with from a police or ambulance siren. It can work at speeds between 0.1 and 10 m/s to measure directly on the material surface with an accuracy of 0.1%, and a repeatability of 0.05%.

The IKO Roofing team at Wigan have been pleasantly surprised by the affordability of the product, and how easy it is to integrate and use with their existing machine set-up. Typically, Return on Investment for a Speetec can be achieved in under 12 months.

Darren Pratt is product manager for industrial instrumentation at SICK UK

For more information: 


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