Commercial Realities - Trialing, Product Development

By Tom Kerchiss, RK Print Coat Instruments

Converters: those engaged in processes such as laminating, coating, and printing must be prepared to explore new possibilities and look beyond the familiar day-to-day routine. They know that their customers, the brand owners, the manufacturers and businesses that have need of their services are generally in for the long haul. No one, least of all suppliers can rest on their laurels. All businesses must continually innovate, look to the future and bring new products to market.  If a converter or a consumable supplier such as the ink producer is unable to meet quality, delivery and other requirements, the customer may go elsewhere. That is the stark reality of being in business.

Unfamiliar materials and processes can prove a learning curve for all concerned. The printer/coating or laminator practitioner for example, may look to using one of its commercial lines for experimentation and the trialing of materials. While this may seem feasible, machine time is often expensive and availability limited. Moreover most production machines will have been designed for a set purpose. They lack the flexibility, instrumentation and often the capability for the interchangeability of components such as different coating applicators, drying modules, etc.

When using a production machine the operator and converting plant manager may be under pressure to rush experimentation in order that the coater/laminator, press, etc., is put back into production as soon as possible. This means that an organization more often than not does not have the luxury to be able to run with ideas and explore new ways of doing things.  

Some companies either use an older machine, or one set aside for the purpose of trialing products. While this may seem ideal, this too has disadvantages.  Processing different products may be limited by factors such as the machine’s ability to run complex substrates due to issues such as the age and condition of the machine and lack of sophistication. Web control, tension regulation and out of tolerance issues can give cause for concern. Rollers are particularly susceptible to out of tolerance disturbances.

Any web operation is dependent upon components working in unison. This is certainly the case with rollers over which the substrate passes as it proceeds through a specific process. Rolls need to operate synchronously in order to ensure that a web is kept on the centerline. Roller misalignment can be a cause of wrinkles, especially when handling thin films; nip rollers must provide uniform nip pressure and operate at the same rate and together to avoid any slip between product and roller. If there is any slip between product and roll, problems such as loss of register and other inconsistencies will occur and with alarming frequency.

One of the difficulties with roller synchronization and slip related problems is that the symptoms can be attributed to other areas, which means tracking down the real cause can be time consuming. Also it is worth bearing in mind that often with an older machine process inconsistencies will become more noticeable over time.             

High levels of waste, web breaks and loss of colour from station to station as well as non-uniformity in coating, etc., often indicate that components need to be evaluated or replaced. Line speed can play a decisive role in the drying of coating products. Line speed difficulties may manifest themselves in various ways, and although speed may not seem on the face of it to be a major concern when trialing or undertaking R & D, a slow line speed or even a fast line speed may test ones patience.

For instance: a heavy coat weight may take longer to dry simply because there is not enough dryer capacity.  If a line speed is slow a newly coated web, perhaps one of a thermosetting nature will be affected by excessive dwell time in the following way: the longer dwell time will cause the temperature of the coating to spike causing a chemical reaction that in turn leads to an excessively cured product. Another downside of too slow a line speed is that with a liquid coating if it remains on its travels through a dryer too long a coating may start to blister or pucker. 
Tension regulation is an area of concern at the best of times but can be even more troublesome if an older less responsive method of tension control is in place.                                                    3

It is impossible to control a web without proper tension control being applied. Tension regulation is necessary to keep webs in traction with idler and driven rolls. Factors affecting the longitudinal dynamics of the web include changes in operating conditions, torque variations caused by an unbalanced roll, wound in tension variations and other periodic disturbances.
When tension is too high webs may stretch in the longitudinal direction and compress in the cross machine direction. Conversely, when tension is too low webs may shrink in the machine direction and web width will widen in the cross machine direction.  If tension is too low or too high web wrinkles will occur.

Inadequate tension control in laminating raises its own set of problems including, lay-flat difficulties to de-lamination, and with printed films image elongation. Poor tension control and the inconsistencies it causes affect so many aspects of production including the ability to obtain maximum yield from the film roll.
The subject of tension control and other aspects of web control are worthy of several articles in their own right; suffice it to say that methods relating to the control of tension on older machines, whether at the unwind, mid-processing machine zone or at the unwind are often found wanting in an older machine, particularly one that has not been subject to upgrades for a while.

The two options that have been mentioned, using an existing production machine or bringing in to service an older machine are far from perfect.

Over the last decade or so the requirements of production, down gauging, the processing of ultra-thin films at high speed and the depositing of ultra-thin coatings has placed greater demands on both printing and converting machines. To address many of the processing issues that arise and which cannot be addressed by using elderly equipment that are often well past their prime a new generation of quality control, product development tools, ones that can undertake small scale production runs have been developed and have come on stream.  

Pilot coating/printing/laminating systems such as the VCML Lab/Pilot Coater and RK Print Coat Instruments flagship high-tech built customer bespoke VCM Coater speeds product development times and provides numerous productivity and commercial benefits.

The VCM Coater is a unique and ambitious product concept. Each system is configured to meet the known and explicit requirements of the customer. Designed and built under the strictest of customer confidentiality agreements The VCM can be used for developing and testing coating formulations, testing ink/substrate receptivity, trialling and pilot runs and the specialised production of high tech items, security and other products. Users can opt for a machine configured for clean room conditions, flame proofed, with corona treating technology and with coating and print head technologies ranging from knife over roll, gravure-offset (printing and coating), hot melt, extrusion, meter bar and much else.  

The VCM is ideally suited for converters and producers of products such as adhesives and additives, chemicals and substrates and for top of the line process and product development organisations. In many respects this is a machine of specialisation and is often up for consideration when a standard off the peg system proves unsuitable.

For many converters, etc., research organisations, laboratories, etc., that may not know from one day to the next what they will have to mount on the machine and process the Rotary Koater might be the solution. The wide range of interchangeable print and coating heads ensures that a user can assess and determine which is the ‘best technology’ for the job.

Configuration options include choice of web paths and drying/curing technologies, wet or dry laminating and the option to select from fifteen different print and coat systems.

The VCML LAB/PILOT COATER is available and is ideal for undertaking R & D, quality control, trialing materials/processes, etc. It can print, coat and laminate all types of flexible substrates such as paper, film, metallic foils, etc., and can employ coatings as varied as inks, paints, varnishes, adhesives both solvent and water based on a reel to reel basis. The machine is able to undertake small scale production and it can undertake meter bar coating, slot die, flexo, direct/revers/offset gravure, differential offset gravure as well as rotary screen, knife over roll. Highly configurable it can be configured with an ATEX compliant coating zone.

RK Print Coat Instruments Ltd
Litlington, Royston, Hertfordshire SG8 0QZ 
www.rkprint.com sales@rkprint.com

Source: RK Print Coat Instruments Ltd