When rolls develop chatter, feedlines and barring, you might use a roll grinder to maintain them to be as round and concentric as possible. However, this roll maintenance is best left to experts who provide roll grinding services to companies on a day-to-day basis.
A perfectly maintained roll increases your profitability, revenue and productivity. It provides better product yield and reduces downtime and operational interruption. But when companies choose to rebuild their own in-house roll grinder, they lose out on the potential benefits of a perfectly smooth, round and concentric roll.
If you already have a roll grinder, it’s likely that you’re going to use it – especially considering its perceived cost. But should it break or need to be rebuilt, it may be in your best interest to change your approach.
Here are five reasons why you shouldn’t rebuild your roll grinder:
Excessive Usage Costs
It costs over $600,000 per year to run the typical grinder full time with a four-man crew. This includes electrical, lighting, supply, environmental, labor, benefits and other overhead costs. It is often not financially practical to bear the expense of owning your own grinder.
Astronomical Rebuild Costs
The typical rebuild of a roll grinder costs up to $1 million. If your rebuild requires an upgrade to current software and drives, an upgrade of obsolete electronic control components and another upgrade to improve grinder technology, it’s going to come with a significant price tag.
Working rolls run “face to face,” and the dimensions on these positions are the most critical. Grinding a roll in its bearings and housings doesn’t enable the grinderman to meet the desired OEM specifications. Barring and chatter cannot be eliminated this way, and the bearing seats are rarely maintained. Grinding on the bearings of a roll often results in more chatter sooner and elevated eccentricity.
Many of today’s machines run faster than their original design, and many mills actually have tighter tolerance specifications. Hitting specified parameters on most modern equipment and machines (those built from 1970 on) is extremely difficult to achieve with the bearings and housings installed. These high-speed machines and converters must produce very precise products. But the only way to meet those demands is to use perfectly shaped rolls.
Cost Efficiencies Of Roll Grinding Services
There’s a misguided assumption that outsourcing is an expensive option – across all industries, but especially when it comes to roll grinding. The reality is that using a subcontractor for precision grinding is typically more cost efficient than doing so in-house – including freight costs.
Operational Efficiencies Of Roll Grinding Services
In order to provide maximum productivity, your rolls must have the exact specified profile, shape, TIR and roundness. If ground to exact specifications, a roll’s crown is perfectly centered on the roll in 360 degrees, and your machine runs more smoothly and quietly.
Such precise roll grinding significantly increases the life of your roll and cover, requiring less grinding and, most important, reducing future downtime. Rubber, poly and composite covers last longer because of the exactness of the grinds, consistency of wear and uniform surface finish.
Whereas it’s virtually impossible for an in-house team to achieve perfect specifications with older grinders, expert roll grinders have such capabilities. Your customer is able to run their converting equipment faster because of the increased uniformity in your sheet. This, of course, translates to greater profitability.
While using your own roll grinder may be an efficient use of your maintenance budget, it’s far more likely that the costs associated with both your equipment and your crew’s lack of expertise (due to turnover) outweigh the expense of outsourcing to an expert.
Set the bar at perfection, and enable your productivity, revenue and profitability to soar.
To learn more about how PRG provides roll grinding, repair and maintenance services that extend the life of your rolls and increase your productivity, click here.