Why plants wait too long on spare parts, and impactor curtain care
Frank AggregateMcLanahan's aftermarket director spent 21 minutes this week on why plants wait too long to order parts, and Eagle Crusher wrote up the impactor curtains that most maintenance routines skip.
| Featured this week | |||
|---|---|---|---|
Director of Engineering, Dry Processing · McLanahan
|
Director of Aftermarket Sales · McLanahan
|
M
Service Technician · Eagle Crusher
|
Production Supervisor · Bastrop Sand Supply
|
Why plants wait too long to order the part
McLanahan's aftermarket director on the two ways downtime happens, and the recommended spares list that almost nobody orders.
On Thursday McLanahan posted a 21 minute Groundwork episode on spare parts with Dan Holes, its director of aftermarket sales, and Tyler Piper, director of engineering for its dry processing group. Holes draws the line where the cost sits: a planned outage costs what you scheduled, an unplanned failure snowballs, and a trunnion roller pushed past its life on a rotary breaker can take the shaft, the tire, the sprocket and the drive with it. What still surprises him after 25 years is that the recommended spares list shipped with a new machine almost never turns into an order. His advice is plain: keep the critical spares on the ground, log what you do to the machine, and let the OEM's service crews look it over before something that is not smoking fails.
Listen to the 21 minute episode
Three opened in September, all of them limestone
Fifty new operations so far this year. Texas holds a third of them, and none belongs to a national producer.
| Fischer Minerals, Williamsburg MO | Crushed limestone |
| Nickel Rock Materials, Limestone TX | Crushed limestone |
| Monarch Pit, Lueders TX | Dimension limestone |
September has three so far, two of them in Texas, and the Lueders pit cuts building stone rather than crushed rock. Thirty-one of the fifty new sites this year are sand and gravel, and the majors are still growing by buying rather than digging.
The impactor parts most maintenance skips
Check the curtain gap every day, flip the primary before the wear reaches the eye, and move the secondary's good top liners down before you buy new ones.
Most impactor advice stops at the rotor and the blow bars. On Wednesday Eagle Crusher's Service Questions series, with service technician Mark, turned to the primary and secondary curtains, the aprons the rock breaks against. The gap between the blow bars and the secondary curtain sets the product, since nothing leaves until it fits through, and the rule of thumb is a 3:1 ratio between the two settings, checked daily through the inspection door. Uneven wear on the rotor or the curtains usually means return material landing on one side, and a diverter chute on the return conveyor evens it out. The primary curtain flips 180 degrees once the top wears to the eye; past that it can fall. The secondary's liners flip too, and a good top row moves to the bottom before you buy new.
86,000 tons a month through one wash plant in Bastrop
Louis Monreal runs a Terex AggreSand 206 seventeen hours a day, and the dewatering screen's moisture control is the feature that sells his sand.
Last Friday Powerscreen Texas published a profile of Bastrop Sand Supply, southeast of Austin, where production supervisor Louis Monreal has run a Terex Washing Systems AggreSand 206 since 2017. Colorado River deposits go in; concrete sand, fill sand, bull rock, 3/8 inch pea gravel and 1, 1.5 and 2 inch gravel come out, 86,000 tons a month with the plant running 17 hours a day. The part Monreal rates highest is the 14 by 6 foot dewatering screen at the end of the machine, which makes up to 200 tons an hour of sand at the moisture his concrete customers want, in his words 95% of the time. Screen changes, he says, are easy, and the parts arrive on time.
Seven ways to get more out of a screen, starting with a two hour audit
Measure stroke, speed and angle at all four corners before you change any media. MAJOR's typical targets are 8 to 12 mm, 800 to 1,000 rpm and 18 to 22 degrees.
Last Thursday MAJOR published seven methods for screen efficiency, ranked by impact and by how fast they can be done, and three of them cost nothing but attention. A vibration audit with accelerometers on each deck corner takes under two hours and shows the stroke, speed and angle the screen actually delivers against what the material needs. A sieve test on today's feed, not the feed from commissioning, sets the opening; if the near size fraction within 25% of the opening exceeds 30%, expect pegging. And feed spread across the full deck width: a 20% improvement in distribution typically brings 10 to 15% in efficiency, the cheapest fix on the list. The other four sell Flex-Mat and sensors, which is fair enough from the company that makes them.
Comments