The Indiana Clean Manufacturing Technology and Safe Materials Institute
2655 Yeager Road, Suite 103, West Lafayette, Indiana 47906-1337
CHILD CRAFT INDUSTRIES, INC.
OPPORTUNITY ASSESSMENT REPORT
In November 1995,
Child Craft Industries, Inc. initiated a joint project with the Indiana Clean
Manufacturing Technology and Safe Materials Institute (CMTI) to investigate methods to
reduce emissions of volatile organic compounds (VOCs) into the atmosphere from the
companys furniture coating operation.
Child Craft Industries, located in Salem, Indiana, produces quality childrens furniture (such as cribs, changing tables, bedroom sets, and desks) for the national and international market. The company designs, constructs, assembles, and applies furniture-quality finish systems to all its products. Currently, the company employees more than 500 employees.
Child Craft is a preeminent manufacturer of high quality childrens furniture. The company is committed to delivering leadership in fashion, value, and quality. The company brings this same commitment to its corporate environmental policies. Child Craft was among the first in the industry to employ the use of electrostatic spray techniques, which increases finish coating transfer to the subject part, dramatically reducing overspray.
Once the furniture units are assembled, they are conveyed through the finish coating department on a serpentine conveyor line. The finishing process can range from a three to four step process to as many as eight steps, depending on the piece being finished. A typical finish process can include the following coating applications:
1. NGR (non-grain-rising) stain, which adds color and enhances grain contrast
2. SAP (dye stain, color adjust for the sap wood) stain, which evens out the stain color match on special veneer panels
3. Washcoat, which smoothes out stain color variation and limits penetration depth of wiping stains
4. Wiping stain, which adds depth and contrast to the woods natural pattern
5. A sealer coat which seals the open pores of the wood in order to limit the woods unnecessary adsorption of the final lacquer topcoats
6. Lacquer topcoats, which form the protective and beautifying finish coats--there can be as many as four coats of lacquer or as few as two
The serpentine finishing production line is operated in a continuous method so that each of the above finish steps are accomplished at set stations as the furniture is conveyed through each station. Thus, the finish system and application process is finely-tuned in order to exactly meet the product rate (speed) of the serpentine conveyor system.
CMTIs experience at several wood furniture manufacturers suggests that bypassing the spray application process of the stain and modifying it to a 100% manual application, could potentially achieve reductions in the use of the stain. This reduction will then translate into reduced VOC (volatile organic compound) emissions and raw material cost savings. The team also estimated a substantial reduction in stain usage. The following assumptions and suggestions were made:
1. Wiping stain usage calculated at approximately 2,500 gallons per year
2. VOC emissions are estimated to be approximately 17,575 pounds per year
3. Spray application of stain and subsequent wipe-off of excess stain estimated at 30% transfer efficiency
4. Estimate sponge reservoir wiping rags transfer efficiency to be approximately 75%
The Child Craft/CMTI team reviewed several processes. Given that any change must not interfere with the current production methods and rates, it was decided that the teams initial project would investigate a modification of the current staining process and not change any raw materials.
The current wiping stain process requires four or five people. One person sprays the stain onto the assembled unit, and then the unit is thoroughly wiped down by the other team members. The team suggested that sponges be placed inside the wiping rags, acting as an on-demand reservoir for stain during the stain wipe-on process. Thus, the three people traditionally involved in wiping off the stain would be utilized to wipe on the stain. The team estimated that modifying the stain process could reduce the stain workforce by one.
The company experimented with the new staining process, at full production for several days, and reported mixed results. The company runs many different types of models through the finishing line. Some of the models design and geometry lent themselves to the new staining method, However, other models (units with numerous routed designs and/or finely recessed moldings) were difficult to adapt to the new stain method. The rag-covered sponge was not able to deposit stain to 100% of the routed (grooved) surface and/or to the fine recesses of the molding.
POTENTIAL ENVIRONMENTAL AND COST BENEFITS
Potential VOC reduction of 6.2 to 7.2 tons
Potential Annual Savings:
1. Raw material: $15,400 to $17,400
2. Reduced towel usage: $4000 to $5,000
3. Reduced labor costs: $20,000
Total potential annual savings: $40,500
Quality is Child Crafts hallmark, and it will not be compromised in the pursuit of cost savings. The current production schedule is based on customer demand, and long runs of any one model type cannot be assured.
Therefore, the company cannot adopt the new method for the design models that lend themselves to the rag-covered sponge method and then rapidly switch to the previous method for the geometrically challenging units. Consequently, the sponge reservoir staining method will not be adopted due to the routed design of some of the units. However, the modified method can produce significant savings when compared to the more traditional spray stain method. Other companies may wish to investigate the reservoir sponge method and adapt it to their finish lines, where applicable.
The Child Craft/CMTI team will investigate other issues such as optimizing the electrostatic spray application and improving air flow patterns within the finish line in order to minimize draft cross-talk (draft air currents between departments) and potential particle contamination on newly sprayed units.