WHEN ZERO WORKS BETTER THAN NOTHING

The manual grinding operation of this Australian foundry experienced low retention, high absenteeism and serious injuries. Then an ergonomic zero gravity dynamic lift assist was installed that eliminated injuries, boosted productivity and let operators maneuver the grinders as if they were weightless, with complete freedom of motion required for the job.

The Bradken foundry at Cromwell Road in Kilburn, Australia been in operation since 1949 as a major supplier of metal castings, primarily to the mining industry. The plant has the capacity to produce 12,500 tons of metal products annually with a workforce of 180 employees. Manual grinding has traditionally played a big role in this operation.

The manual use of heavy hand-held grinders is a typical requirement of casting, forging and metal fabrication. It is demanding and tiring work that places considerable stress on the user and, as a result, grinding is often considered to be one of the least desirable assignments and faces low retention and high absenteeism. The Kilburn foundry had experienced all of these problems and more, including 14 injuries attributed to grinding over a 24-month period – four of which resulted in employees being placed on restricted duties.

The foundry faced some serious problems: for a typical shoulder injury, direct medical costs can exceed $20,000. Indirect costs associated with lost time, retraining, etc., can be a multiple of direct costs, with total injury costs reaching $80,000 or above for a single injury. Some dramatic changes had to take place in the grinding process.

The plant searched for a technology that could dramatically increase worker productivity by reducing fatigue. They found an answer in zeroG®, an ergonomic zero gravity tool balancing system developed by mechanical engineering firm Equipois, Inc. (Los Angeles, CA). This patented lift assist provided a solution for component grinding that both reduced injuries and boosted productivity by letting the operator maneuver the grinder as if weightless while preserving the complete freedom of motion required for the job.

The system follows these specifications:

• The dynamic lift assist will provide a full dynamic range of motion to allow users to utilize tool in a similar fashion to how it is used without a lift assist.
• The dynamic lift assist system will utilize no electrical, pneumatic or hydraulic power source. Lift and motion will be achieved 100 percent mechanically (i.e. zero power consumption).
• The dynamic lift assist must be able to support grinding tools weighing between 8 lb (3.63 kg) and 36 lb (16.33 kg).
• Typical allowable grinding tools will include standard right angle grinders, in-line grinders and vertical grinders.
• The fixed pre-set mount lift assist system will provide a working range of at least 58.63 in (1489 mm) from the mount.
• Utilizing the Heavy Jib reach extension, the working range for the system will be a radius of at least 141 in (3581 mm). The system will allow grinding for components as long as 240 in (6096 mm).
• The Portable Gantry mounting option provides a top mount linear rail to allow the grinding system to be mounted above or alongside the work area. Linear rails come in standard length of 72 in (1829 mm); 96
• in (2438 mm); and 144 in (3658 mm).
• The zeroG4 Quad Stand portable cart mounting option provides a completely mobile, small footprint cart to bring the grinding system to almost any location where it is needed.
• Cabling such as pneumatic air lines, power cords, hydraulic hose or sensor wiring can be routed along the length of the dynamic lift assist arm to a termination point.
• The dynamic assist arm and any reach extension must be mounted to a structure that has the ability to support the full system and payload. Maximum moment load considerations for the structural design can be found on the system installation drawing.
• The dynamic lift system will include protective covers, which will prevent grinding sparks and other corrosive elements from damaging the arm while also protecting the user from pinch points.

The system immediately reduced operator fatigue and the potential for injury in the foundry. Injury rates dropped to zero. The total hours required for grinding-related tasks were reduced by over 60 percent, and operators were able to use more powerful grinders to further increase productivity.

Prior to installing the new system, the damage of cords and hoses of grinders was common during usage. With the zeroG® system, the cables and hoses are now festooned along the length of the arm to prevent damage. By running power leads through the structure, even trip hazards were reduced. By using the new system, tools are no longer dropped when not in use and tool repair costs have reduced. Grinding disc usage has reduced by 30 percent to 40 percent because the grinders are now held in an optimum position to use more of the pad with proper pressure with the new balancing system. This generates costs savings of $500 to $1000 per year or more.

In foundry grinding applications, the degree of precision can often be challenging when using a heavy tool. With the zeroG® arm, foundry operators can now utilize their fine motor skills to be more precise, improve the quality of the process, and reduce the number of rejected parts.

Absenteeism in the grinding area was immediately reduced by nearly 50 percent due to the improvement of worker safety and morale. Aside from the importance of stabilizing a critical stage of the manufacturing process, this ergonomic grinding system generated immediate operations savings of $219,720. After subtracting $9000 a year for depreciation and $750 a year for maintenance, the total net savings gained by using the new system was $209,970.

But that’s not all. The total cost to acquire and install the zeroG® system was $36,000, which means it only took a little over two months (.17 years) to pay back the entire investment in the system. The return on investment (ROI) was a compelling 583 percent!

Equipois Inc., 5440 McConnell Avenue, Los Angeles, CA 90066, 310-736-4130, [email protected], www.equipoisinc.com.