Origins (Polyethylene) Fabrication & Installation
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Whether the material is Origins Patterns, Origins Solids or Origins Quick Ship, it is all high-density polyethylene HDPE #2. Creating something with it requires various fabrication & installation techniques that we have described below.
Safety First: Always wear safety glasses when cutting polyethylene or any material. Hearing protection is advisable when using power equipment. Respiratory protection should be used when a dust producing operation is being performed, such as sanding. Gloves or tongs should be used when thermoforming to prevent burns.
General Machining Characteristics: Polyethylene is machinable using standard wood and metal working equipment. In some cases, certain adjustments must be made in cutting speeds and feed rates for lower heat distortion temperatures to avoid heat build-up from tool friction. For optimum tool life and accuracy, carbide or diamond tipped tooling is recommended. Tools should be kept sharp and smooth, with good side clearance angles. Water-soluble coolants may be used. Material to be machined should be supported and clamped to minimize vibration (which can cause chipping and rough edges).
Saw Cutting: Polyethylene can be cut with all types of saws. Handsaws, hand power saws, jigsaws, band saws, table saws and computer controlled saws. The optimum circular saw blade for cutting polyethylene is a 1/16” kerf, carbide tipped, triple chip 2.5 tooth per inch saw blade with a 2 deg negative hook angle. Slower feed rates will minimize chatter marks on the cut edge. The index surface of the material (that which is in contact with the saw table or base) should be protected from abrasion with wax, tape or chipboard. Waxing or lubrication of tool base is also recommended. Saw blade chatter marks will be visible on the cut edge and will need to be removed for fine work.
Water Jet Cutting: Polyethylene can be successfully cut with a water jet. Complex patterns can be cut from a CAD file with remarkable accuracy. The deeper the cut, the rougher the edge. Thus, thinner panels will have the smoothest edges. The water jet channel marks will be visible on the cut edge and may need to be removed for fine work. If the panel being cut has the factory applied peel coat masking on the index side (facing down on the table) the exiting water jet has a tendency to mix with the water-soluble adhesive and leave a sticky residue on the exit surface that must be cleaned off. If removing the peel coat masking to avoid this, be sure the cut panel will be handled carefully to avoid scratching.
Shaping: Polyethylene panels can be run through a shaper to profile edges. High-speed steel or carbide tipped cutters quickly remove material leaving a crisp slick edge. Good material handling and material surface protection is essential.
Turning: Polyethylene can be satisfactorily turned on a lathe. Cutting tools with a negative back rake and front clearance will give the best results. Feed rates of 0.02 to 0.10 inches per revolution and turning speeds of 250 to 750 surface feet per minute give the best turning results.
Milling: Milling at 500 to 1000 sfpm should give good milling results
Reaming: Fluted reamers are recommended. Speed is approximately the same as for drilling.
Deburring: Polyethylene can be deburred with a deburring tool. The deburring tool is an inexpensive hand tool that bevels edges, working best on interior curve edges.
Edge Planing: Polyethylene can be planed with hand and hand power planers. These tools are useful for beveling or easing edges to relieve the edge sharpness left by most cutting operations. Planes are also useful for reducing the width of panels by slight amounts.
Sanding: Polyethylene can be sanded for decorative effect, to remove or hide scratches and in surface preparation. Hand sanding is often used for small area surface preparation when adhesives are going to be used. Hand-held electric or air sanders are used for sanding large and/or irregular shaped areas. Wide belt sanders or abrasive planners can be used to create a brushed look. CNC sanding can be used to apply a consistent swirl pattern. Coarse grit such as 40, 60 or 80 will produce a suede-like finish. By stepping up the grits, by no more than 100 at a time, a very smooth surface can be achieved with 600 grit papers. All sanding produces airborne dust.
Mechanical Fasteners: Screws and bolts are a common and very successful fastening method. To avoid the material splitting in the future, predrilling the hole for the fastener is recommended. Properly installed threaded inserts and through-bolts are the best way to firmly secure polyethylene to many other materials.
Why Predrill for Fasteners? Polyethylene is denser than wood and does not have the cell structure that will collapse to accommodate fasteners such as screws, nails, and staples like wood does. Although a fastener entering polyethylene without a predrilled a hole will cause the polyethylene to melt slightly around the fastener and secure it in place better than in wood, the risk of future breakage outweighs this advantage. Also, fasteners entering polyethylene without predrilled holes tend to cause the polyethylene to bulge upward around the fastener, reducing the strength of the joint.
Laminating: Polyethylene can be laminated to itself and other substrates. The highest quality lamination of polyethylene to polyethylene is in a compression molding press. With this method, several thicknesses of material can be laminated together to form a 100% bond. When different color panels are used, the laminated panel becomes suitable for engraving or edge profiling. This method of lamination requires no surface preparation. When laminating to wood or any other material, abrade the side of the polyethylene to receive the adhesive with a 36 to 60 grit paper. Apply a good grade of contact cement per the label directions. With contact cement lamination, the exposed seams may still be welded using adhesive or heat. The various adhesives tested and approved for use with Origins are:
1. 3M #4693 Contact Cement leaves a visible glue line.
2. Loctite Super Bonder Products #s 414, 416 and 454 w/ 770 primer. A cyanoacrylate that leaves an invisible glue line.
3. 3M #DP-8005 or DP-8010 Scotch-Weld Structural Plastic Adhesive leaves a whitish glue line.
Welding: Polyethylene can be welded using a plastic welder and a polyethylene-welding rod. There are several types of plastic welders available. The joints made with a plastic welder are as strong as the material itself and are highly recommended for edge joints. In some cases, the plastic welding rod can be cut from the material to be welded, which allows for the weld joint to become invisible. The simplest type welder produces a stream of hot air and can accept various different types of welding tips. Another welder heats up the edges of each material and injects heated welding rod into the joint. Some plastic welding suppliers are:
Seeley Inc, hot air type, requires electricity and compressed air.
Kamweld Products Co Inc, hot air type, requires electricity and compressed air.
Drader Manufacturing, injector type, requires electricity and compressed air.
Abbeon Cal Inc is a distributor of plastic fabrication equipment.
Maintenance: Other than occasional cleaning with soap and water, very little maintenance is required for Origins panels. Abrasive cleaners and cleaning pads should be avoided. Food preparation such as cutting or grating should be done on a cutting board and a trivet or hot pad should be used to protect the surface from hot containers. The surface should be kept free of abrasive materials such as sugar, salt, and sand. Avoid sliding heavy objects across the countertop. These should have rubber feet or other protection for the surface. Origins is embossed with a texture at the factory to minimize minor scratching, however, usage will eventually cause some scratches to develop.
Prevent Damage During Installation: Prevention of damage is important to consider. When installing, keep the factory applied peel coat masking on the exposed surfaces as long as possible. When other trades may be in the same areas after your installation, cover the surfaces with a thick material such as the chipboard the Origins panels are packed with, corrugated cardboard, plywood or pressboard. Ideally, blocking access is recommended, keeping in mind that most blocking can be gotten around.
Prevent Damage During Use: Simple steps can be taken to keep the installed Origins looking good and be free of scratches. periodic cleaning of the surface depending on the conditions. Do not slide heavy objects across the surface. Make sure heavy objects have soft feet, such as rubber or felt.
Minor Repair Methods: Some scratches may be partially healed by applying pressure with a hard, smooth object such as a spoon and rubbing with the direction of the scratch. A deeper scratch can be removed by sanding, however, this will change the sheen of the surface. Thus, the entire surface would need the same amount of sanding to match. Coatings such as silicone or floor sealer may work for hiding minor scratches. A test should always be conducted on a small piece of the material before applying it to the entire top.
Handling: Always protect both surfaces of the panel material from abrasions of any kind when handling Origins. Tape, paper, chipboard, and cardboard are all readily available materials that can be used to protect the surfaces while you handle and fabricate the material. Origins ships interleaved with protective material to ensure it arrives in prime condition.
Preparation for Cutting: Origins ships with its mold edges attached. The mold-edge protects the panel during shipping. The mold-edge must be removed before the panel can be cut to size. When using hand power tools, a clamped straight edge is required for at least 2 adjacent corners. When using CNC machines, accurate placement of the panel is important. There is no guarantee that the mold edge will yield any additional usable surface area, although sometimes there is.
Laser Cutting: Polyethylene can be successfully cut with a laser. Testing the laser on the material to be cut is recommended because the power of the laser must be matched with the thickness of the material for a crisp clean cut. One technique to consider is masking the penetration surface of the panel with a paper tape. Complex patterns can be cut from a CAD file with remarkable accuracy. The deeper the cut, the rougher the edge. Thus, thinner panels will have the smoothest edges. The will Laser beam channel marks will be visible on the cut edge and may need to be removed for fine work.
Die Cutting: Polyethylene can be successfully die cut in the 1/8 thickness only. The top edge will be slightly eased and the bottom edge will be sharp. The material in the selected color type should be tested first. The number of parts that can be cut at one time depends upon the pressure exerted by the die cutting machine and the design/strength of the steel cutting rule. This is a high-speed way to produce large quantities of the same part. Examples of typical edge smoothing are tumble polishing, buffing, and router trimming.
Routing: Polyethylene can be routed with handheld and CNC routers. High-speed steel or carbide tipped cutters quickly remove material leaving a crisp slick edge. Good material hold-down is essential. Routing is used for cutting out irregular shapes, edge profiling, milling and engraving. The industry standard edge finishing for polyethylene is a router trimmed edge. Router trimmed edges should be radiused or beveled with ball bearing guided router bits to provide a safe, finished product.
Drilling: Polyethylene can be drilled by hand, with hand power drills, drill presses or CNC drilling. The faster speeds produce holes with slick interiors and crisp clean edges w/ no surface deformation. Virtually any type of drill bit works. Drilling is required when using mechanical fasteners. Recommended feed rate is .004 to .020 inches per revolution, deep holes require backing drill out of hole periodically to remove chips. Drill specifications for optimum results are as follows:
Tap & Die: Threads both male and female can be successfully cut into polyethylene. Generall,y tap and dies of 2 or 3 flutes and a slightly negative rake work best. While operating, the tap or die should be periodically backed off to clear chips from the threads.
Thickness Planing: Polyethylene can be successfully thickness planed with a knife or abrasive planer. Begin by reducing the thickness by no more than 0.010” per pass. Depending upon the type of knife planer used, the surface may show knife marks.
Sand Blasting: The surface of polyethylene can be altered by sandblasting. Thus, text and other decorative designs can be embossed on the surface or the surrounding surface can be sandblasted, leaving the pattern area unchanged. Sandblasting is also an efficient way to cover very large areas quickly.
Polishing: Polyethylene can be polished. As the final step after sanding to 600 grit, hand or power buffing using an automotive or plastic buffing compound will result in a highly polished surface. Edge polishing can be achieved with a cloth buffing wheel. To polish and ease edges at the same time, 2 or more cloth buffing wheels may be ganged on the same arbor.
Decorating: Polyethylene can be decorated with ink or paint. Silkscreen inks and paint have been developed for polyethylene but all require that the surface of the polyethylene be treated to allow adhesion of the ink or paint. Plastic decorating is widely used in the automotive industry. The surface treatment is called oxidation and this is accomplished by any one of the following:
1. A blue flame passed over the entire surface to be decorated. The flame must pass by fast enough not to distort the material and it must be the blue portion of the flame.
2. Sulfuric acid w/ specific gravity of 1.82 (must be contained in a glass bottle to be strong enough bath, dip or application w/ polyethylene or polypropylene bristle brush. Allow standing for 5 to 10 minutes before rinsing off.
3. Corona treatment of the surface using an electrical discharge. This method only works for extruded or blow molded polyethylene because a consistent thickness and surface properties are required.
4. Plasma etching is another method of surface oxidation.
5. Sanding is another method that will allow the ink or paint to gain a purchase on the polyethylene.
Watertight Bonds: If strong watertight bonds are required for edge gluing, use 3M #DP-8005 or DP-8010 Scotch-Weld Structural Plastic Adhesive.
Tack Welding: Polyethylene tack welds with a plastic welder, a soldering iron, a wood burning tool and even a clothes iron. These welds are produced when the hot tool is run along the seam where 2 pieces of polyethylene are touching, producing a thin film of polyethylene joining the two pieces together. Though not strong, tack welding is used primarily for positioning to allow another fastening method to be used.
Stake Welding: This is a process where 2 polyethylene panels are placed together to be joined. One panel has one or more holes drilled in it, the diameter being determined by the strength required of the joint. The Plastic welder is then used to weld the 2 panels together through the drilled hole. Care must be taken not to use too much heat or else the opposite side will show signs of heat distortion.
Vacuum Forming: This method works best when only one side is required. This is because the side receiving the heat tends to distort due to the original compression molded resin components of flakes and or pellets. Extruded polyethylene vacuum forms very well, resulting in both sides being smooth.
2-Part Mold Thermoforming: Origins is most successful when using a 2-part mold, where both surfaces of the heated material are pressed between two mold surfaces and allowed to cool in the mold. Depending upon the part configuration, sometimes the ends or edges of the formed part require being “captured” as part of the installation design. Capturing keeps the edges where they are wanted and alleviates the chance of the part warping.
Major Repair Techniques: Noticeable but minor scratches can be healed by carefully applying heat lightly to only the scratch with a plastic welding torch to cause the material to “flow” back together. Larger scratches or deep gouges are best repaired with a plastic welder and then carefully sanded and buffed to match the surrounding area. Caution: if not done properly, serious damage can result.
If heat is not practical, some scratches and mars can be repaired with the adhesive listed herein. Epoxy glue and auto body putty can also be considered. Drill a few 1/32″ holes in the deepest parts of the area to act as anchors for the adhesive. Then cover the surrounding area with wax or very thin tape. Mix up a small batch of 5-minute epoxy and tint it with color pigment if desired. Add the mixture to the depression, being careful to fill up the cavity and the anchor holes.
Place a waxed piece of a hard material with a texture like the marred surface, over the epoxy and clamp or apply weights in order to apply as much pressure as possible to produce some adhesive squeeze out. This will ensure a similar texture on the repair’s surface. When the Epoxy has set, remove the clamps or weight and peel off any thin layers of adhesive squeeze out and clean off the wax. Trim with a razor if necessary. When done correctly, it will be difficult to detect the damaged area.
Plugging is another repair option to consider. This requires a drill, a plug cutter on a drill press, a scrap material of the same color and preferably one of the recommended adhesives. After the hole is drilled and the plug is cut, apply a very small amount of adhesive to the sides of the hole and gently tap in the plug until the surfaces are flush. Trim with a razor blade if necessary.
We hope that some of the Fabrication & Installation techniques for polyethylene described in this section will be helpful to you in determining if Origins Patterns, Origins Solids, or Origins Quick Ship HDPE polyethylene panels are appropriate for your project. Perhaps some of these techniques will be employed successfully as you fabricate and install this useful decorative mater made with recycled plastic.
Please contact us if you need further information or help with a specific application.