One of our core competencies at Optimation is in the development, design, fabrication and improvement of web-based, or roll-to-roll, processes. Optimation owns and operates a web development laboratory – we call it the Media Conveyance Facility (MCF). Many things you use on a regular basis are produced on a web, from aluminum foil to the thin glass used in cell phones.
The processes behind web based or roll-to-roll manufacturing require specialized skillsets to ensure a defect free product and high throughput. In order to better understand what we mean when we refer to this manufacturing method as “roll to roll”, here are some simple questions with answers that can provide you with the basics of web handling.
What is a web?
A web is a piece of flexible material which is much thinner than wide, and much narrower than long. In order for a flexible web material to be processed in a roll to roll production line, it must have a modulus of elasticity such that it can withstand some level of tension (being pulled in the direction of machine travel) without deformation; it must also have a minimum level of lateral stiffness such that it does not easily buckle in the cross machine direction (this is why soft metal foils, like copper, are difficult to convey in a web line).
What is a roll?
A roll is a web wound onto a core. Webs are wound into rolls so that they can be transferred between process steps easily. As you can imagine, a web product in sheet form that might be several miles long would be difficult to handle in its flat form if it were not to be wound into a roll.
What is a roller?
A roller is a cylindrical machine part used to convey webs through machines. Rollers play an integral role in a web line, as they transport the web without product damage from one end of the line to the other and allow the web to have value added processes performed to it (like application of coatings).
What is web manufacturing?
Web manufacturing is any process utilizes a thin sheet form factor to produce saleable goods. Web manufacturing can refer to the process that first constructs a web (i.e. paper making or plastic film extrusion). It can also refer to a process that in some manner performs a value adding step (printing or coating onto the web, treating the web, converting the web, etc.)
What is web handling?
Web handling is a discipline or method that seeks to transport/handle a web while maintaining/preserving all of the web’s properties. Web handling is also responsible for presenting the web in the correct condition or attitude such that other processes (value add steps) can be properly performed.
What is web converting?
Web converting is any process that takes one or more webs and permanently alters them in some fashion. Converting generally refers to changing the web characteristics for downstream use, usually by modifying its dimensions (slitting the web widthwise to create a size or format for downstream use, chopping the web in the cross-web direction to create shortened product rolls or even sheets.
Is web handling an art or a science?
Web handling is primarily a science with a broad array of measurement criteria and engineering based fundamentals that have been developed over years of study, experimentation, and validation. Web manufacturing and converting production methods tend to place emphasis on empirical experience, as many companies lack the research capabilities and tools needed to characterize their products and equipment. This is a somewhat qualitative statement as there continues to be more first order principles-based capabilities being developed and applied to these areas.
What is the history of web handling?
Web handling has a long and colorful history which closely tracks the development of engineering science and the development of web handling equipment. As is often the case with any technology, the two have not always progressed together and in fact, while the engineering science tools predate web handling equipment, the application of the tools to web handling, to a very large degree, actually postdate web handling processes and equipment. The earliest first principles tools arose in the development of solid mechanics (pioneered by the work of Leonhard Euler – mid 1700s) and Newtonian mechanics (pioneered by Isaac Newton – late 1600s). Web handling equipment has its roots during the Industrial Revolution (mid 1700s to mid-1800s). Application of first principles to web handling has achieved its greatest impetus due to the ongoing activities of the Web Handling Research Center at Oklahoma State University (mid 1980s).
How do I know if I have a web handling issue?
The best way to determine if you have a web handling issue is to consider your answer to two questions. These will enable you to quickly determine if your problem is related to web handling:
- Does this problem deal/interact with the web? Or, could it be possible that the web is the root cause, or possibly an influencer to, the problem? When thinking about this question, do not be quick to discount what a web is. It turns out that a web can be just about anything that is thin, wide and long. The principles governing the behavior of a web are applicable to any thin and flexible product including paper, film, metals, nonwovens or textiles.
- Is the problem you are experiencing related to the transport and handling of the web where the intention is to maintain or preserve the web’s properties? Here again, do not restrict your thinking too much. For example, the following would all be viewed as web handling processes: unwinding, splicing, roller conveyance, air conveyance, tension control, web spreading, lateral control, nip mechanics, roll start, roll winding and roll storage. In addition, the effects of web properties such as friction, roughness, modulus of elasticity, thickness variation, and other mechanical attributes are inter-related to web handling processes and, if improperly specified or controlled, would constitute a web handling issue.