Austin Engineering has released a new white paper on ‘Excavator Operator Best Practice – To extend bucket life on mine sites’.
Most mine sites employ a wide range of excavating equipment produced by major OEMs such as CAT, Hitachi, Komatsu and Liebherr to fill haul trucks with coal or overburden for dumping.
These excavators use buckets of two main types - face shovels or backhoe. While face shovels dig forwards with an apron section on the front that opens away to release the product, the backhoe is a one-piece unit that digs back towards the machine.
Mining buckets may be an OEM product or custom engineered by a non-OEM manufacturer to suit site specific applications, while adhering to OEM equipment specifications. When designed by a non-OEM manufacturer, mining buckets are often engineered with specific material types and density, and standard digging practices in mind.
Custom engineered buckets are usually designed to be used in post blasted or loose overburden ground. The bucket and the OEM machine are not designed to dig in-situ or into virgin ground or rock. Pre-blasting and bulldozer rippers are designed for that process.
Unfortunately, mining excavators are sometimes subjected to misuse by an operator who may use the bucket for lifting and repositioning the machine. Using the bucket in this way means the loads are directly opposite to the parameters that the engineer had designed the bucket to handle. Common problems arising out of this misuse include compression of the top box connection areas causing cracking and fatigue; load on the bucket causing bulging of the side walls leading to cracked wear plates; and point loading to the floor ejecting the wear package, buckling or twisting floor plates; and side scraping with the bucket causing it to twist among others.
To prevent unnecessary maintenance expenditure, and extend bucket life, it is important to prevent bucket damage by ensuring best practice in the operation of the excavating equipment. Before any operation commences, the operator must know and understand the limitations and safety aspects of the machine. Custom designed buckets must suit each particular OEM machine, along with site specific conditions, in order to maximise production and life expectancy of the bucket and machine.
The operator is responsible for monitoring the digging conditions and ensuring they are working in pre-blasted ground, which meets the bucket’s tolerances. All digging needs to be completed in smooth actions reducing excessive loads to the machine and attachments.
Before each shift commences the operator should take the time out to physically inspect the bucket for visually obvious changes from the previous inspection, including signs of visual cracking; loose, broken or missing ground engaging tools (GET) or wear plates; and excessive wear areas, especially weld wash around wear plates; and also ensure grease systems are ejecting grease efficiently from each pin; covers are in place for pins and grease lines; bushes are not walking out of bores; and door and jaw are correctly aligned, and cylinders are not leaking in the case of a face shovel.
All findings need to be reported immediately to the appropriate maintenance or asset management personnel to ensure the defects are resolved in their early stages.
A regular routine of pre-shift inspection, along with a focus on keeping within standard digging practice guidelines will result in extended mining excavator bucket life.
Austin Engineering, a leading manufacturer of customised dump truck bodies, buckets and ancillary products used in the mining industry, is also a complete service provider, offering on and off-site repair and maintenance and heavy equipment lifting services to customers.