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Merryweather Foam Blog

Since 1948, we have been industry leaders in fabricating unique, foam components for customers in the medical, sound absorption, automotive, and unique packaging industries. At Merryweather Foam, we pride ourselves on our ability to combine experience, innovation, and excellent customer service. We have the knowledge, manpower & equipment to help you get the job done. Visit our website to see our fabrication portfolio as well as our capabilities.

Twisting the Knife: Complex Shapes from Horizontal Contour Cutting

Horizontal contour cutting is a fast way to cut complex shapes without tooling delays.

The continuous or circulating horizontal bandknife machine slices the largest blocks of foam into thin layers or sheets. Add the ability to rotate the bandknife and the machine becomes a horizontal contour cutter, able to produce complex foam shapes quickly and efficiently.

Operating Principles
The horizontal contour cutting machine looks like a giant upturned "U" bridging a large flat table. An unbroken band of hardened steel runs through this "U", enclosed completely except for the horizontal length above and parallel to the table. This band moves continuously in one direction, with teeth along the cutting edge slicing effortlessly through large foam blocks clamped in place on the table.

Unlike the horizontal bandknife, the contour cutter has three axes of motion. The upturned "U" frame can move forwards and backwards, the band can move up and down, and the angle of the teeth can be changed by applying a twist. By synchronizing the movements of these three axes, the machine can cut angles, curves and even tight radii and sharp corners.

CAD to Part Program
A computer controls the motion, following a program developed from a CAD file of the part. Producing this program usually takes just minutes, although nesting, (adding other parts to the cutting program to minimize how much material gets thrown away) can add more time. A contour cutting machine needs no part-specific tooling, which helps gets the design into production faster and saves money. It's often possible to have pieces coming off the cutter within just a few hours of receiving the CAD file.

Precision Steel Cutting Blade
The band itself is just 0.7mm (0.030") thick and less than 4mm (0.15") deep so it's easily twisted and little material gets wasted. Twelve to fourteen teeth per inch cut smoothly, letting the machine advance the blade at up to15m/minute (49'/min) without deforming the material.

Why Horizontal Cutting?
The choice between horizontal and vertical contour cutting depends on which is the most economical way of getting the shape out of the block. Sometimes the vertical cutter is more appropriate. The horizontal machine is often used for the first cutting operation, followed by cutting in the other plane.

Benefits of Horizontal Contour Cutting

  • Cut complex shapes from large blocks.
  • Smooth edges with no steps or jagged edges in curved surfaces.
  • Tight radii and even sharp corners.
  • Good accuracy and repeatability (little piece-to-piece variation.)
  • No tooling, so no up-front costs or extended lead times.

Merryweather Capabilities
Merryweather's horizontal contour cutter handles polyethylene, polyurethane, EPE, EPS and convoluted foam in blocks as large as 2.3m (90") by 2.3m (90") by 1.3m (51") and densities up to 10 pounds. Programming direct from CAD means the machine is as suitable for producing one-offs as high volume orders.

Flexible and Accurate
The horizontal contour cutter is a three axis bandknife machine able to produce complex foam shapes quickly and efficiently. With no tooling it's suitable for cutting even one-off shapes and precise motion control leaves smooth, step-free edges. Learn more by contacting us with your questions.

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Choosing the Right Foam Product for Acoustical Insulation

Acoustical foam is a cost effective way to improve the quality of sound in a room. Contrary to what many believe, foam does not block sound, but absorbs it. Sound waves propagate through the air and reflect from surfaces to produce echoes. When sound waves enter the pores of the foam, the sound energy is converted to kinetic energy. It is transferred to the foam, causing it to vibrate. This prevents the sound waves from reverberating throughout the room. Acoustical foam is available for use on walls and ceilings. It is frequently used to control noise in auditoriums, recording studios and conference rooms and reduce vibrations in industrial settings.

Types of Foam
Melamine and polyurethane are the primary materials used to produce sound absorption foam. Polyurethane is tear resistant and may be found in a wide range of colors, textures and styles to allow limitless design possibilities. Polyurethane foams are available as either polyesthers or polyethers. Polyesthers are more robust, glossier and maintain their color longer than polyethers. Polyethers are less expensive. Polyurethane acoustical foams are Class B Fire Rated. The material is highly flammable and should not be used near high heat or open flames. Melamine is not quite as durable as polyurethane but has a Class A fire rating. It is often the choice of builders since it meets fire codes. Melamine is fire resistant and used in public areas such as hospitals, schools and cafeterias.

Foam Shapes
Acoustical foams are produced in a variety of shapes and sizes to enhance performance and increase specific sound absorption properties. Convoluted foams, such as the egg crate pattern, are designed to increase the surface area to provide greater absorption of sound waves. Wedge foam, with a one inch thickness, offers moderate sound control and is most effective for mid to high range frequencies. Increasing thickness to 2 to 4 inches increases the foam's ability to absorb a full range of frequencies. Though similar performance improvements are observed with increasing thickness, the increased surface area resulting from the unique geometry of pyramid foam offers a slight performance improvement over the wedge foam.

Application
Acoustical foams are lightweight and easy to install. To be effective, all wall surfaces of the room must be insulated with foam. Applying it to only one wall allows the sound to reflect from the remaining uncovered walls. The type of foam needed to treat your room will depend on the size, shape, surface texture and frequency of sounds.

How can we Help?
Let us help you select the right flexible foam product for your next project. We would love to answer any questions you have about custom foam fabrication.

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Understanding What the Vertical Contour Cutting Machine Can Do

Contour Cutting is an Excellent Capability for Custom Foam Fabrication

It's difficult to cut curved profiles in foam and get smooth edges. Reciprocating tools tend to tear and leave unsightly steps while methods like water jet and die cutting have limitations with thick materials. In these situations it makes sense to use a vertical contour cutting machine.

Operating principle

Like the band saw used in many industries, vertical contour cutting machines use a continuous steel blade held vertically under tension. The work material, (usually foam,) is placed on a flat table that moves it into the blade to make the cut. Looped over pulleys, the blade moves continuously in one direction, ensuring that it's always cutting, (unlike with a reciprocating saw where half the motion is wasted.) Computer control over both the blade and the table motion allows production of complex shapes.

The cutting blade

As with any sawing process, the teeth shape and pitch must suit the material being cut. For foam 12 to 14 teeth per inch usually gives the optimal combination of cutting speed and edge finish. Some materials cut better with a wave form rather than teeth while others need only a flat knife blade.

The blade itself is made from high quality steel and measures 3.6 mm (0.144") deep and just 0.6 mm (0.024") in thickness. This geometry has two benefits. First, being very thin, there's minimal cut waste, which also minimizes the amount of dust produced. Second, it makes the blade maneuverable.

Blade maneuverability is one area where the vertical contour cutting machine differs from a regular band saw. The contour machine can rotate the blade through 360 degrees. Combined with the shallow blade depth, this lets it turn to cut complex shapes without compressing the foam.

Motion control

The vertical contour cutting machine has three motion axes under computer control. The table moves in one direction, pushing the foam through the blade. Carried on a bridge over the table, the blade can move left and right. If the blade and table moved at the same speed a foam block on the table would be cut at a 45 degree direction.

Axis three is blade rotation. It's this which lets the machine cut circles, corners with tight radii and complex contoured shapes. Internal holes in foam shapes are possible with just a single entrance/exit slot, (which is usually needed for fitting around bars, pipes, extrusions, cable conduit and so on.)

Machine capabilities

Merryweather's vertical contour cutting machine handles blocks of material up to 55" by 94" by 25". Cutting speed is as high as 230' per minute, depending on material density and whether bonded or laminated. Materials appropriate for vertical contour cutting include:

  • Polyurethane
  • Convoluted foam
  • Polyethylene
  • Cross-Linked polyethylene (XLPE)
  • Expanded polyethylene (EPE)

Material with densities up to 9 pounds can be cut, as can bonded layers of foam and foam laminated with either foil or textile material.

Process characteristics

  • Straight, smooth sides produced on thick foam blocks.
  • Cuts complex 2D shapes.
  • Programmed directly from CAD files.
  • "Nesting" function in software maximizes material utilization.
  • No tooling, so no tooling costs or delays for tool manufacture.
  • Ideal for small quantity orders
  • Small "kerf" (cut width) means minimal waste and dust.

Quality results

A vertical contour cutting machine is the best way of producing smooth, straight-sided shapes in soft materials like foam. Merryweather's machine handles large blocks of material quickly and efficiently with minimal waste. As no tooling is needed this process is ideal for both small and large quantity orders.​ Not sure if vertical contour cutting is the right capability for your project? Get in touch with us and we will be happy to answer any questions you have about custom foam fabrication cutting capabilities. 

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All About Precision Foam Skiving

​Skiving is a manufacturing technique you don't see very often. Google it and you'll learn about thinning leather or shaping metal gears. What you won't see much of is how it's used for precision foam sheeting.

Skiving foam entails using a sharp knife to cut thin layers from a large block. That's the skiving process. It's different than sawing because that removes material whereas skiving splits it into two parts. It's an excellent way of cutting sheets of foam, which is why we use it here at Merryweather. To learn more about our precision foam skiving capabilities, keep reading.

Skiving basics

Skiving entails pushing a solid block of polyurethane foam through the blade of a knife. The blade is actually a steel belt around 1mm (0.040") thick with a very sharp edge, and is positioned horizontally above the machine table. To help the blade cut it's looped over two drums that pull it perpendicular to the direction the block is moving. These two motions help the blade slice through the material, shaving off the thickness required.

The skiving machine, sometimes called a continuous bandknife or a foam splitter, looks rather like a bandsaw laid down on it's side. Keeping the blade under tension ensures it doesn't sag, so we can cut a block of foam into thin sheets quickly and efficiently.

Advantages

As skiving splits the foam rather than cutting pieces out it, there's no material removal. That gives it five big advantages over traditional sawing-type processes:

  • No waste - Sawing, and for that matter, processes like water jet cutting, have a 'kerf' or thickness of material that's lost. Skiving has no kerf so there's no waste. That helps keep costs down.
  • Dust free - Sawing is messy because the teeth carve away little chips of material. They stick to everything and can never be completely brushed off.
  • Smooth edges - Sawed edges are rough, which looks untidy and creates problems when sheets are put to use. Skiving polyurethane foam blocks avoids this problem, which means no secondary clean-up operations.
  • Close tolerances - A precision foam splitting machine, as we use at here Merryweather, keeps the blade tight and parallel to the machine bed. That ensures tight tolerances are maintained, which means customers receive sheets of consistent thickness.
  • Continuous resharpening - In material removal processes the cutting edge dulls with use, so the last piece cut has a different finish to the first piece. Skiving machines continuously resharpen the blade, so every sheet looks the same.

Merryweather for polyurethane & polyethylene foam skiving

The best way of producing thin foam sheets is by skiving. It's an efficient process that produces smooth, clean sheets of uniform thickness. If you need closed tolerance foam sheets, discuss it with us and we'll explain what skiving has to offer.

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Seven Surprising uses for Reticulated Foam

Ever unloaded the dishwasher and found the spoons or knives didn't come clean because they were stuck together? Well imagine that happening with surgical instruments. Placing instruments in bags made from open-cell foam is one way healthcare professionals avoid this. Steam reaches the surfaces but foam keeps them from touching.

Open-cell is another term for reticulated foam. One way of visualizing reticulated foam is to picture a mass of bubbles, then think how they'd look if the wall between each bubble was removed. Effectively, you'd have a three dimensional mesh where every cell is open to its neighbor. Cell size and density are controllable during manufacture. Density is specified in terms of pores per linear inch (ppi) and is controllable from 4 to 100 ppi. (A larger number means smaller pores.)

This results in some interesting and useful properties. Reticulated foam is compressible, yet springs back when the load is released. It's lint-free, porous, and at under two pounds per cubic foot, lightweight. As a result, it's used in a very wide range of applications. Here are some that may surprise you.

  1. Blood filtration and oxygenation. Heart-lung machines put oxygen back into blood, but tend to create bubbles. Passing the blood through a felted reticulated foam breaks these up, making it safe to return to the body.
  2. Air filtering. From automobile cabin air filters to nebulizers, there's a long list of air filtration applications. Even small lawnmower engines use reticulated foam to prevent dust and grit from being sucked in.
  3. Filtering molten metal. In casting, as metal is poured into a die it's important to remove impurities. Reticulated foam wouldn't withstand the heat; instead it's dipped into a ceramic slurry which dries to leave a more durable, heat-resistant mesh.
  4. Stabilizing fluid in tanks. Gasoline in an empty tank will slosh about, but fill that tank with reticulated foam and the gasoline moves slower. The foam can also help dissipate static, reducing the risk of fire if the tank ruptures. (Ink jet printer cartridges are a similar reservoir-type application.)
  5. EKG pads. Electrical conductivity between skin and electrode pads is improved with a specially formulated gel, but applying this adds a rather messy step. Reticulated foam EKG pads are pre-impregnated with the gel, saving time on prep and clean-up.
  6. Sound absorption. Reticulated foam makes an excellent windshield for microphones. Sound still penetrates but wind buffeting is absorbed, eliminating most background noise.
  7. Surgical instrument sterilization. Discussed before, reticulated foam: allows steam to penetrate, stops instruments touching, and avoids lint carryover.

Is your application next?

Reticulated foam is surprisingly versatile. With an open cellular structure it can filter or stabilize fluids, so finds application in areas ranging from motorsport to healthcare. If you're interested in learning how this lightweight material could benefit you, contact Merryweather today.

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