Considering a Slitter purchase: What do “TCO” and “robust” mean, and why are they important?
There are two phrases often heard these days during discussions with customers considering a new slitter. Customers will often talk about their focus on “TCO” (Total Cost of Ownership), and machine vendors will use the word “robust” to describe the nature of what they build. What these terms mean, why they are important and how they relate is something every machine buyer should understand and consider.
Companies today, from large multi-nationals to small entrepreneurs, understand that ownership costs are more than simply the purchase price of a piece of machinery. There are ongoing operating costs that will continue for each day the slitter is in service. TCO also considers these costs in the form of maintenance and downtime. Therefore, the three main elements of TCO are:
- Cost of purchase. The obvious one is simply what it costs to buy a slitter and have it installed on your floor. Depending on the application and model, there can be a wide distance between the lowest cost and the highest. For a generic duplex, fixed shaft slitter rewinder, prices can range from 1.5 to 2x for the same basic functionality. There are significant differences in the machines of course, but when looking strictly at purchase price, those differences are not in the equation.
- Maintenance costs: There are two new converting realities today that have a major impact on maintenance costs. One is increased operating time. Demands, in terms of hours of usage, on slitters has increased dramatically. Multiple shift operations, including a lot of 24/7, have become commonplace. The other factor is machine speed. Until recently, a common answer to the question “how fast do you run,” was between 800 and 1,200 fpm. Today, it is common for a slitter to run at 2,000 to 2,500 fpm, or more. The combination of more hours of operation and faster speeds have made machine build quality, aka “durability”, the critical element in keeping the maintenance cost element of TCO controlled.
- Downtime costs: Downtime, those hours when a slitter is not producing product, may not readily be associated as a “cost”. However, when a machine is not running it is not producing revenue. Operational reasons for downtime (changing out master rolls and finished sets, splices, etc.) are effectively minimized in design considerations and plant operational procedures. Downtime for maintenance or breakdowns also need to be minimized. How is that accomplished? Two areas should be evaluated:
- First, the quality of the build, aka the “mechanical robustness” as described above, is one major consideration. This is where durability becomes key. A good definition for durability in this context is “a build quality that considers and responds, in design and manufacture, to the high operational hour demands and speeds of today’s slitter environment.
How does a machine buyer assess a machine’s durability? What should be looked for? There are a number of items easily observed. A few of the most obvious are:
- The unwind: This must have heavy-duty spindle bearings and pedestals. These are essential to withstand the abuse the unwind will take from loading of heavy rolls and constant guide shifting.
- Roll diameters: Idlers should be larger diameters to avoid critical rpms at today’s higher speeds. Pull rolls should be of sufficient diameter to prevent slipping and to assure unfailing web tension control.
- Shear tooling: The female shear shaft should be larger as well to minimize the wear of higher rpms and to provide a stable knife mounting to minimize blade wobble.
- Rewind spindle bearings on cantilevered rewind shafts must be heavy duty for rigidity and longevity. This is a critical element of a quality build; no acceptable compromises here!
- Ballscrew driven pusher that contacts and pushes against the core, not the material.
- Roll trees, cantilevered in design, must be heavy-duty to stand up to the greater weights of today’s large rewind diameters.
- Second is the service response capability of the vendor. Every hour a machine is down costs money. Waiting days for a return call, or for a conversation with someone with the required technical expertise is painful, costly and frustrating. What to look for here?
- The machine should be equipped for remote support. Typically, over 90% of service calls can be addressed online. Even those that require a vendor visit can be prepared for when online diagnostics have been performed.
- Is 24/7 service availability important? The answer is, only if the person answering the phone at 3:00 a.m. on a Saturday morning is knowledgeable! It is important to ask how many field service technicians are on the vendor staff and what their levels of experience are. Answers to these questions are the best indicator of a vendor’s ability to respond quickly when your machine is down.
Summary: Every capital purchase in converting is critical, perhaps none more than for a slitter rewinder. The slitter is usually the last value-added step, as it transforms materials that have had several upstream value-added processes invested into to the finished rolls that the customer will receive. Minimal waste and maximum throughput are essential. The machine that provides the lowest TCO is rarely the one with the lowest price tag. Rather, it is the one that is robust; built for hard duty and backed by a company staffed to support it promptly and competently when needed.
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