Practicing routine grinding machine maintenance produces productivity gains

Because of the array of precision functions grinding machines perform, it’s vital to properly maintain them to keep them operating at their peak in terms of accuracy and reliability. You can start by devising a maintenance program and sticking with it. This article provides tips on how to set up key parts of that program. The tips apply to virtually all types of grinders, including surface, OD, ID and rotary ones.

A mechanic removes the magnet from a surface grinder for cleaning. Keeping scale and corrosion from accumulating between the bottom of the magnet and the grinder’s subtable is a must to help ensure accurate grinding. All images courtesy of Pyramid Rebuild & Machine.

While metalcutting professionals understand that grinders must be properly maintained, that doesn’t mean it gets done. Frequently, production demands elbow out maintenance chores and before long, the results of neglecting machine care become painfully evident. Inaccurate parts, breakdowns and even safety hazards can result. To avoid potential injuries, costly remedial action and lost production time, shop managers must first identify the maintenance requirements for each grinding machine and use that information to craft a comprehensive maintenance program.

A maintenance program should include a method of determining when each maintenance task was performed and by whom to help ensure accountability.

Clean the Machine

Keeping a grinder clean is a no-brainer, right? Yet it’s not uncommon to walk into a shop with hundreds of thousands of dollars of precision grinding equipment and see a grimy mess on every machine. A chief reason for this is the grinding process itself. Grinding produces swarf, a mixture of minute metal particles and abrasive material that quickly works its way into a grinder’s clearance areas and crevices. The problem is particularly common on rotary and centerless grinders because of the large volume of material they are able to remove, and it can cause serious damage if left unchecked. Therefore, it’s vital that a procedure for cleaning grinders is developed and followed.

It’s not enough just to wipe off exposed surfaces on a machine. A cleaning plan must identify the hidden areas where swarf tends to collect and describe how to clean those sections. Water guards, way covers and clearance areas between slides are areas where swarf tends to collect and cause problems. In some cases, the only option is to remove the component for cleaning. Use a scraper or wire brush to remove heavy debris and hot water for lighter debris, such as coolant residue.

Keep an eye on coolant. Over time, coolant becomes contaminated and can develop corrosive characteristics that eat machine components. Contaminated coolant can damage everything from machine guards to way surfaces to lubrication lines. Periodic cleaning of the coolant storage tank and filtration systems is a must.

The coolant mixture itself should be adjusted according to the manufacturer’s recommendations to ensure the coolant is still doing its job. If OEM specifications are unavailable, consult a coolant manufacturer.

Monitor Lubrication

Grinders can require costly repairs if their lubrication systems fail or do not operate at 100 percent efficiency. Way lube systems on grinders are typically a terminal design, which means they consume oil. If operators don’t have to add oil to the way lube system on a regular basis, then it is probably not working properly. To keep terminal lube systems operating properly, lubricant levels must be rigorously maintained.

It’s also critical to use the correct lubricant. Don’t assume the right lubricant is what you’ve always used. Review the OEM specifications or ask a lubricant supplier.

In addition, clean the lube reservoirs and change the filters at least every 6 months. Visually inspect the way surfaces at 6-month intervals to make sure lubricant is being delivered properly. The ways should be clean except for a thin film of lubricant. Dry ways indicate a lube system malfunction that must be addressed immediately.

During the visual inspection, note the way wipers. These wipers are not present on all grinders, but when they are they must be kept in first-rate condition because wipers remove dirt and contamination from the way surface. Adjust any wipers that are not fully engaged on the way surface and replace those that show signs of deterioration. It’s best to err on the side of caution in this regard. When in doubt about the condition of a wiper, replace it.

Another key task is examining the lubrication system’s lines. It is common for swarf buildup and the corrosive action of rancid coolant to damage grinder lube lines. Replacing damaged or broken lines is critical because most grinders have a “parallel” type of lube system. On these systems, the lubricant follows the path of least resistance, so a single broken line can defeat the entire system. That results in some surfaces receiving too much oil and others not receiving any. If left unchecked, premature wear of the way surfaces will result.

Beware Gummy Gibs

At least once every 6 months, remove and clean the gibs on a grinder’s vertical slide. Usually, common hand tools are all that’s required to remove the gibs. Once removed, clean them by scraping off heavy contamination and then remove any remaining contaminants with hot water followed by thorough drying and applying a light coating of way oil. Though somewhat time-consuming, this task is necessary because coolant mist dries on the gibs, making them prone to sticking. Gummy gibs strain the vertical slide leadscrew and accelerate wear on this costly precision component. Worn lead screws can reduce accuracy and must either be replaced or rebuilt. In addition to being costly, the process is likely to sideline a grinder for weeks.