The 4 most common ‘Difficult to Rout’ materials used in the construction industry

In their quest to find the right functional design and modernity and to design something environmentally friendly and durable architects seem to be ever specifying harder, more abrasive and more exotic board products or board product replacements. This is often done with very little regard to how the material or part is to be machined.

Here's some information on the 4 most common materials in the construction industry that we get asked regularly how to cut:

Fire Retardant MDF Boards

Fire Resistant, Fire Rated, and Fire Retardant boards are designed to help stop fire and heat from spreading.

Whenever a fire develops in a building, it is important that the fire stays where it is and that load-bearing structures maintain their load-bearing capabilities for a time sufficient to enable people to evacuate and rescue operations to be carried out. Fire protective boards are resistant to the heat and radiation of the fire. 

Find out all the benefits in our instructional video.

How are they resistant and why are they difficult to cut?

Fire retardant wood products are typically created through the use of organic and inorganic salts, which are infused into the wood through water-based solutions under pressure. The end result is a product that has 0.2 to 1.13KGs of salts per cubic foot of wood product.

As you can imagine, the salts are incredibly abrasive and cause immense heat when cutting. This heat build up bluntens tools extremely quickly.

Cutting MDF creates a very fine chip which must be extracted well to avoid the tool clogging, breaking or leaving burn marks in the slots and shapes being cut for panelling and additionally, this fire-rated MDF often has a veneer on the top and bottom that must be cut cleanly without chipping.

This is why our PCD diamond compression cutters are the best option. The PCD (polycrystalline diamond) diamond tips are over 20 times harder and more heat tolerant than tungsten tools so are able to stay sharper for longer in the extremely hot and abrasive cuts. The single flute style of the tool allows for better chip extraction & better plunging ability for slots and the compression style helps to prevent chipping or fluffing on both sides of the boards.

Fibre Cement Boards

Fibre cement is a simple abbreviation for Fibre Reinforced Cement. Fibre cement building materials were developed by James Hardie in the early 1980s.

Engineered for durability, fibre cement is fire resistant, rot resistant and resistant to moisture damage, making it the ideal low-maintenance alternative to traditional building materials.

What’s inside that makes it extremely abrasive to rout?

Fibre cement is a mixture of:

• Locally sourced cellulose fibre, from plantation grown Radiata Pine trees
• Portland Cement
• Sand
• Water

The concept of routing something with cement in it probably explains the reason for its difficulty to rout. The mixture of cement and sand is obviously extremely abrasive but surprisingly, the special paper layer on the outsides of the panels is thick and also wears cutters quickly as well.

Again, PCD diamond cutters are the best option. The harder diamond tip lasts longer and our Straight diamond cutters have a small amount of upshear on the tips to help with shear off the paper layer and improve dust extraction. These are available in the smaller diameter because of the need for companies to create designs in fibre cement board for artwork on building cladding.

Compact Laminate or Phenolic

Compact Laminate is a common name for phenolic resin sheets (such as Fundermax - Phenolic Resin Panels for Exterior Application). It's a new environmentally friendly material that is resistant to acid, alkali, fire, moisture, and collision. 

It is:

• Anti-impact
• Wear resistance
• Non-toxic, non-polluting, completely hygienic
• Moisture-proof, waterproof, mildew proof
• Chemical resistance
• Heat resistant and resistant to smoke
• Anti-static, no radiation
• Antibacterial, easy to clean, UV resistant

How is it made and why is it hard to rout?

The HPL Board is made of decorative confetti impregnated with melamine resin, laminated with multi-layer black or brown kraft paper impregnated phenolin resin, and then pressed with steel plate through high temperature (150 ° C) high pressure (1430 psi) environment, and baked. A process called polymerisation melds them all together creating a solid-core panel.

The phenolin resin used in compact laminate product is very hard and its also very expensive. This means a lot of manufacturers in the interest of saving costs are resorting to replacing some of this resin with other even more abrasive products such as urea (which is like cement). This is why there is a lot of variation between brands as to how they cut, the best speeds and the best cutters for it.

Here a few options of tooling providing excellent results when cutting phenolic / compact laminate.:

• Solid Tungsten Upcut Cutter for Phenolic and Composites - 3 Flute
• PCD Shear Cutter for Compact Material & Laminates
• Solid Tungsten Marathon Compression Cutter - 3 Flute
• Solid Tungsten Carbide Stub Drills

High Pressure Laminate on Plywood

HPL, meaning “High-Pressure Laminate” is a kind of engineered plastic material. After the plywood has been produced, HPL is covered onto the face/back of plywood under high pressure. That’s what is called “HPL Plywood”. It’s used widely in kitchens, bathrooms and commercial cabinetry.

Why is it particularly difficult to rout?

The hardness of the High pressure laminate (a thin, man-made composite material made up of many layers. At its core are compressed sheets of paper impregnated with thermosetting resins, typically phenolic, that are bonded together and occasionally reinforced with metal layers or mesh) along with the adhesive layers in the plywood combine to make this board very abrasive to cut. Standard tungsten cutters burn up and get lines cut into them from the HPL layer very quickly.

Again, for long-term success, PCD diamond is the go-to. The harder diamond tips are able to handle the abrasive layers better and last a lot longer but there are a few options of tooling, depending on the amount needed to be cut. 

Some HPL Plywoods like the Polaris HPL from Plytech have a thicker 1mm layer of HPL. For this board we recommend the 3 Flute Plywood Diamond Compression as the HPL is too abrasive for the single flute diamond cutters.

• Tungsten Chipbreaker Compression Cutters
• Single Flute Eco Diamond Cutters
• 3 Flute Plywood Diamond Compression cutters 

Read more about the tooling options HERE to work out what’s going to be best for you. 

Watch our instructional video to find out what is the best way to cut plywood.

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