Air force

Courtesy of Dantherm Filtration

Dust collection systems need to be inspected and repaired on a regular basis. In this photo, a Dantherm Filtration technician works on a rooftop dust collection system.

The last thing managers at small and medium-sized job shops want to think about these days is spending money. Yet there are a few shop improvements that may be worth investing in. One is indoor air quality (IAQ).

Cleaner plant air can increase morale, employee productivity and part quality. Also, IAQ can affect machine tools, which are more susceptible to damage and distortion due to particulates in the plant’s air than ever before. This is because tolerances are becoming tighter (some say precision machining is going to be measured in angstroms in the near term). A particle of dust can distort accuracy in ways not clear to the eye, but very clear to precision measuring devices.

Plant air, therefore, is headed towards the same environmental requirements as clean rooms used extensively, for example, in the semiconductor industry, according to some experts.

Besides those concerns, there is also an ever-growing body of federal and state regulations on air pollution—for inside and outside the plant. The number and complexity of these regulations is staggering, but you still must deal with this “regulatory fog.”

The two most important federal agencies to track and communicate with are the Occupational Safety and Health Administration and the Environmental Protection Agency.

Inside Out

A simple regulatory rule is “inside the shop it’s OSHA and outside it’s EPA,” according to Joe Topmiller, technical sales manager, United Air Specialists Inc., Cincinnati.

But there are other organizations that companies can look to for direction when choosing an air cleaning system, including the National Fire Protection Association, Quincy, Mass. It is the responsibility of the manufacturer to ensure that air handling and air cleaning systems are equipped with features that provide safe venting of explosive events or safe suppression of explosive events when handling potentially combustible dust. Two particular NFPA standards to note are No. 68, which deals with explosion protection by deflagration venting, and No. 69, which covers explosion prevention or suppression systems.

Compliance can be costly, but spending on IAQ upgrades can bring clear benefits to the bottom line, according to Joe Snyder, a CNC machinist based in Jackson, N.J. “Everyone talks about increasing production and part quality by fine tuning cutting conditions or selecting proper tools,” Snyder said. “There is one aspect many people do not address: the psychological effects of working conditions in a shop environment.”

Many shops, he continued, have welding, fabricating, assembly and paint areas. All can create health and safety issues and “an environment that is detrimental to machine accuracy and life,” Snyder said.

Like a Clean Room?

In effect, regulation and the need for higher part quality are driving machine shops and fabricators to become more like semiconductor production clean rooms, with ever-cleaner air to improve both employee health and machine accuracy.

For example, Trostel Ltd.’s Polymer Compounding Div. (PCD), Whitewater, Wis., uses two ceiling-mounted cartridge dust collectors from United Air Specialists to capture carbon black dust before it lands on four DC motors that power a dump and blend mill. The dust collectors also provide a continuous airflow to keep the motors from burning up. Previously, the company used cooling fans, which would pull dust into the motors, frequently shorting them out, according to Jayson Irwin, Trostel facilities engineer.

The entire Trostel facility is some 28,000 sq. ft., but the area of the mixing operations is about 7,000 sq. ft. When Trostel PCD’s maintenance staff was evaluating clean air solutions for their 33-person facility, the company had five goals:

• keep conductive dust from being pulled into the motors by the cooling fans,

• improve air quality,

• reduce employee risk,

• reduce maintenance, and

• reduce downtime.

And all five goals needed to be accomplished with a system (or systems) that would pay for itself in a year and fit into a small space. This was made possible with the installation of two ceiling-mount cartridge dust collectors that were directly ducted to two mill motor intakes. “The dust collection equipment easily paid for itself in less than 12 months,” Irwin noted. “We went from servicing each of the four motors about four times a year to not having to touch any of them for 14 months.” Considering the cost of downtime and fees to fix the motors, this turned out to be a $35,000 to $50,000 a year savings.

According to Topmiller, a reputable company should be able to evaluate a facility and provide several solutions for a given process. For example, there are often multiple choices of systems to provide clean air within a facility. Equipment recommendations can vary drastically according to a facility’s unique layout, process and usage, and the most cost-effective system for one company may not be the same for another.

“Generally, it is recognized that employees are a company’s greatest asset,” said David P. Jones, sales manager, Air Cleaning Equipment Inc., Broadway, N.C. “Lost time and turnover can result in many negative results. I find it unconscionable that employees are asked to tolerate [poor air quality] conditions. Regrettably, the effect of ignoring this problem is difficult to quantify.”

Jones added that a shop is more likely to retain employees when attention is paid to the workplace environment. “I have had quite a few operators express appreciation for their employers concern with regard to air quality concerns.”

Where do you begin? “Housekeeping problems can be reduced when attention is paid to the source of the problem,” Jones said. “When I go into a shop and see machine coolant dripping from the ceiling and overhead ducts, I know we can greatly improve the overall environment in the shop with properly applied equipment.”

Costs and Savings

One way to look at the cost is to consider the savings of an air cleanup effort. “Consider the cost associated with the loss of coolant and lubricant into the atmosphere. Systems can capture this material and return it to the process machinery, resulting in a tremendous operating savings,” Jones said. “A low-cost, general-purpose soluble cutting fluid will cost $15 to $20 per gallon. Condensing machine oil mist that would otherwise escape into the shop environment and returning it to the machining center reduces the amount of fluid that must be purchased. If you just save 1 gallon a day from one process machine, over a year you save almost $2,000,” Jones added.