Eliminate Costly Machine Downtime Due to Tailstock Failure
The fact is that a lot of machinery becomes obsolete before its time, and the original OEM may not exist anymore to provide timely replacements. If a machine becomes obsolete, Riten has developed a dedicated tailstock "rebuild-repair" program that allows manufacturers to strategically schedule downtime. Indiana's Deister Machine can attest to the success of the program.
Deister Machine is known for its separating and sizing equipment that is engineered to operate hour-after-hour, day-after-day, with minimum attention and maintenance.
Since 1912, Deister Machine Company, Inc. (Deister: Fort Wayne, IN) has been manufacturing quality specialized vibrating equipment for the mining, quarrying, and allied industries. The family-owned and operated company is a preferred manufacturer of vibrating feeding, scalping, and screening equipment. Deister is known for delivering reliable separating and sizing equipment that is engineered to operate hour-after-hour, significantly increase efficiency and productivity within key aggregate industries including: crushed stone, sand, gravel, asphalt, coal, coke, slag, and ore processing.
Deister's dedicated aggregate capital equipment portfolio includes machinery for inclined screens, high-speed screens, horizontal screens, asphalt-batch plant, asphalt-drum mix, dewatering screens, feeders and grizzlys, and electro-mechanical feeders.
In 2006, Deister realized that their lathes required excessively frequent maintenance, which was affecting their production output and resulting in costly downtime. In turn, they contacted Riten who swiftly performed essential inspection-and-failure analysis on one of their two lathes.
Complete tailstock showing replaceable point.
Based on their findings, Riten designed and manufactured a new quill with an upgraded four-piece bearing design. This new design was an upgrade with more capacity than the existing bearing design. They also designed and manufactured a replaceable point spindle instead of the existing solid spindle, since the customer noted that the spindle points of their existing lathes were easily damaged. This new design was highly efficient and performed much better than the old design.
A year later, however, Deister came back with a desire to achieve additional bearing life. Riten then initiated a review of the application on-site and discovered that part of the process involved an eccentric load that they were not aware of. Eccentric loads are very hard on both the bearing assembly and the spindle of the lathe.
Old bearing assembly showing six bearings separated by a spacer, with replaceable nose. This is a used assembly in for repair.
New bearing assembly with the old-style solid nose, prior to redesign of nose.
The review revealed that Deister was turning shafts that weigh between 1,500 - 3,000 pounds. Once these are turned complete, they cut a new center hole that is offset (not on-center) and turn a new bearing journal -- resulting in a shaft that is unbalanced. In effect, a heavy, eccentric shaft spinning at high RPM can literally walk-the-machine across the floor, which is extremely hard on the equipment and its effective lifespan. However, this shaft design is key to the performance of equipment Deister is known for.
Again, after reviewing the application on-site, Riten suggested key changes to both the process and their selection of dead centers. In addition to premature wear on the bearing assemblies, they were breaking dead centers -- a vital safety concern. In many cases, their center hole sizes were inadequate, therefore, charts were provided that specified minimum center hole sizes based on the weight of the part.
Additionally, the bearing assembly in the new unit was upgraded to a matched set of six angular contact bearings. The existing four-bearing assembly was replaced with a six-bearing assembly in the same custom quill. When designing the quill, room was left in the assembly for additional bearings -- if they proved necessary.
VIDEO: Deister equipment in action
Another key downtime dilemma is delivery on a bearing assembly, which can be anywhere from 12 - 20 weeks depending on availability of the base bearing. The bearing manufacturer starts with a standard high precision bearing and reworks them into a six-bearing matched set. Riten orders and inventories a spare bearing assembly with every customer repair. This is essential for limiting production downtime for a repair -- reducing downtime to 2 - 3 weeks vs. 3 - 5 months for the repair.
Between 2006 and 2010, Riten upgraded a total of three Deister lathes -- two of which are identical. They all share the same bearing assembly and replaceable point. The upgrade included manufacturing new quills with replaceable point spindles and honing the tailstock to fit. Notably, the new tools were installed on-site.
In addition to repair services, Riten Industries, Inc. designs and manufactures tailstock conversions and upgrades. This tailstock quill features interchangeable noses. The tailstock was converted from a dead tailstock to a live tailstock at the customer's request.
With this established "shut-down elimination" program in place, Deister continues to have Riten refurbish one of their lathes each year during their slow season -- with each lathe being refurbished approximately every 2 - 4 years depending on their usage.
According to Riten's V.P. of Manufacturing, Mitchell Kirby, "It's imperative for companies to perform critical maintenance during seasonal downtimes on their lathes. Depending on business levels, more companies send us their damaged units annually for either refurbishment and/or replacement. We also manufacture spare identical quill assemblies for inventory. With this in place, we can limit their downtime to 3-5 days to remove the existing unit and mount the spare, whereas delivery on a replacement unit could be 14-18 weeks."
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