Technical Report #19 - Chelsea Center for Recycling and Economic ...
available. Extrusion is a sophisticated process and using high-quality, consistent, dry wood fiberis critical. About the cheapest good grade for decking will be 5 to 5 ½ cents delivered. A onecentchange in wood flour translates to about 1 ½ cent change per linear foot in product cost.(Note: the use of fiberized wood does have the potential of enhancing the structural properties ofthe composite.)Resin: (47% of composition) Resin prices are at an all time low. It is hard to justify usingrecycled at current prices. Recycled also has much more variability. Prices are predicted to staylow for the next two to three years. A 3-cent change in resin prices changes product price about 4½ cents per lineal foot. Bulk delivery and storage are the most cost-effective ways to handle theresin.Additive package: (3% of composition) This includes UV protection, lubricant, and colorif needed. A 30-cent change in the additive package will change the product cost about 3 cents.Machine time: Machine time will vary depending on capital costs, labor costs, etc.$100/hour is a reasonable estimate based on industry standards. A $10/hr shift will change productcosts about a nickel.Throughput: Throughput is the critical component in product cost. It is determined by anumber of factors and is not an exact science. Additive packages, pumping capability of the extruder,tooling, and desired product quality all affect throughput. Three and a half feet per minuteis a fairly typical rate. Some manufacturers do much better, others do worse. Depending onthroughput, each line should make between 1.5 and 3.5 million lineal feet/year, based on a 24-hours per day, 7 days per week operation.Engineering the profile: Manipulating the cross section of the extruded profile to maximizethe use of the material is the second most critical component to keeping costs down.Some composite manufacturers produce a solid component; others engineer and produce a moresophisticated profile which may require a higher quality raw material. Product cost can be reduced20 to 30% by engineering a profile.Manufacturing Cost Summary: Concentrating on good profile design and manufacturingefficiencies (throughput) are where the money is made in this market. Everyone pays about thesame for resin, wood flour, additives, trucking, etc.iii. Testing of Composite DeckingTesting of composite decking varies widely from manufacturer to manufacturer. Trex iscertainly one of the leaders with a great amount of useful data. Making and selling a productwhose failure could conceivable result in serious injury or death tells the wise manufacturer tohave extensive property data and manufacturing documentation.In addition, failure due to poor UV stabilization or poor encapsulation of the wood couldresult in numerous deck surface replacements that are still under warranty. Such a failure couldeasily bankrupt even an established company.Mechanical Property Testing: Fortunately there are a number of standard ASTM tests(D198) that can be conducted to ensure adequate composite decking performance. They includetests for:a. Lumber Bending Strength, or Modulus of Rupture (MOR)b. Lumber Bending Stiffness, or Modulus of Elasticity (MOE)c. Lumber Compressive Strength54
d. Lumber Compressive Stiffnesse. Hardnessf. Fastener tests1. Nail head pull out2. Lateral nail resistance3. Screw withdrawal4. Nail withdrawal5. Linear change with moistureg. Linear change with temperatureh. Water absorptioni. Thickness swellAccelerated Aging Tests: Because composite decking products are used in outdoor environments,it is anticipated that physical aging will play an important role in their long-term performance.For this reason, some of the tests described above should be repeated for a matched setof specimens after the specimens have been subjected to the accelerated aging specified inASTM D1037, sections 118-124. This accelerated aging exposure is intended to be a “measureof the inherent ability of a material to withstand severe exposure conditions.” This exposure, andsubsequent testing, will provide a comparative measure of the performance of the wood fiberfilledplastics against conventional wood products.iv. Comments on Composite DeckingComposite decking may present the greatest opportunity for the wood-plastic compositesdescribed in this report. It is generally more expensive than traditional treated lumber, cedar, orredwood, however its contribution to the total installed cost of a deck is modest. The public isattracted to composite decking because of its perceived low maintenance and durability.Anyone entering the composite decking market is advised to thoroughly test the finishedproduct and document the manufacturing procedures to protect itself against liability and warrantyclaims.XII.SEMINAR PROGRAMPart of this project was to organize a seminar at which findings of this investigation aswell as other technical and market information on wood-plastic composites would be presented.The purpose of the seminar was to stimulate interest in the production of composites in Massachusetts.The seminar was held on October 7, 1999 in cooperation with the Chelsea Center. Presentersand their subjects were:Introduction to The Program, N.C. Weidhaas, Forest and Wood Products Institute, MountWachusett Community College, Gardner, MA andJodie Siegel, Chelsea Center for Recycling and Economic Development, Chelsea, MA.The Wood Residue Situation in Massachusetts, Gordon Boyce, Department ofEnvironmental Management, Commonwealth of Massachusetts, Amherst, MA.55
AN INVESTIGATION OF THE POTENTIAL T
VII.7. Efforts to Improve Products.
LIST OF GRAPHSGraph 1: Cost of Virg
I. ABSTRACTThe market for wood-ther