CNC cutting and water jet cutting can both cut rubber with efficiency and precision. What’s the best way to cut seals, gaskets, or insulation then? This article compares CNC cutting vs. water jet cutting and considers the advantages and disadvantages of each process. Elasto Proxy provides water jet cutting services, but we want to help you make the right choice for your project.
CNC Cutting vs. Water Jet Cutting for Rubber: An Overview
The table below provides an overview of key differences between CNC cutting and water jet cutting for rubber.
Factor | CNC Cutting | Water Jet Cutting |
Types of Cuts | 2D cuts from flat sheets | 3D cuts from extrusions 2D cuts from flat sheets |
Heat Generation | Generates heat, which can deform the rubber | Cold cutting process, no heat damage |
Material Thickness | Generally limited to thinner materials | Capable of cutting thick rubber with the use of a water-borne abrasive |
Tool Wear | Tools wear out over time | No tool wear because the cutting is done with water |
Production Speeds | Faster, especially with simple cuts | Slower, especially with thicker materials |
The following sections compare these two cutting processes in greater detail.
What is CNC Cutting?
CNC cutting uses computer numerical control (CNC) and direct physical contact to cut through a material. Pre-programmed computer software guides the machine and a tool cuts through the workpiece. Because the machine is computer-controlled, there is minimal human involvement once cutting begins. With rubber products, a rotary tool or knife makes the cuts.
There are many different types of CNC equipment, and CNC machines are used to perform tasks that include the milling, drilling, and turning of metal and plastic. For cutting rubber products, however, CNC routers are used typically. These flatbed or gantry-style machines have X and Y axes that control horizonal movement and a Z axis that controls the up-and-down movement of the tool.
Advantages of CNC Cutting for Rubber
There are four main advantages to using CNC equipment to cut rubber.
- Accuracy: CNC machines are highly accurate and can produce parts with relatively tight tolerances. Remember, however, that rubber has different tolerances than metal.
- Speed and Volume: CNC machines are faster at making simple cuts with thin sheet materials. In turn, this supports the higher-volume production of parts like flat gaskets.
- Versatility: CNC machines can handle a wide variety of rubber compounds and can produce parts in a range of shapes, patterns, and designs.
- Automation: Once the cutting program is created, CNC machines can run automatically with limited human intervention.
Disadvantages of CNC Cutting for Rubber
Despite its advantages, CNC cutting has some disadvantages when it’s used with rubber.
- Heat Generation: CNC cutting can generate heat, especially with thicker materials. This can deform rubber or cause an elastomer to lose its properties. For example, EPDM and silicone may become less flexible.
- Limited to 2D Cuts: Most of the CNC equipment that’s used to cut rubber can only handle flat sheets. You could use a multi-axis CNC machine instead, but cutting is slower and more expensive.
- Tool Wear: Rubber can be abrasive, and the cutting tools that are used with CNC machines wear over time. When tool replacement or sharpening is required, manufacturers pass along these costs to customers.
Water Jet Cutting
Water jet cutting uses a high-pressure stream of water to cut through materials. For softer materials like rubber, pure water jet cutting is typically used. For harder and thicker rubber, and for non-elastomers such as metals, the pressurized stream of water is mixed with an abrasive. Water jet cutters include flatbed equipment, but multi-axis robots are also used.
During water jet cutting, the cutting stream is directed at the rubber material at high speeds. The cuts are clean and precise, and water jet cutting is an especially good choice for heat-sensitive materials since it’s a cold cutting process. Like CNC cutting, water jet cutting is also computer-controlled for part-to-part consistency.
Advantages of Water Jet Cutting for Rubber
Both CNC water cutting and water jet cutting are accurate, versatile, and automated. In addition, water jet cutting provides three key advantages.
- Cold Cutting: Rubber is sensitive to temperature changes, and high heat can cause elastomers to warp or degrade (i.e., lose their properties). One of water jet cutting’s main benefits is that it’s a cold cutting process that does not generate heat.
- No Material Deformation: Water jet cutting does not put mechanical stress on the workpiece material. With rubber, this is another significant advantage since elastomers tend to deform under pressure and may bend or stretch during cutting.
- Thick Material Compatibility: When an abrasive is used, water jet cutting can slice through thick rubber materials. Depending on the composition of the rubber and the settings of the water jet, it’s possible to cut rubber that’s up to several inches thick.
Disadvantages of Water Jet Cutting for Rubber
Despite its advantages, water jet cutting for rubber has some disadvantages.
- Speed: Water jet machines are slower than CNC equipment overall. Thicker rubber takes longer to cut than thinner rubber.
- Volume: Because water jet cutting is slower, it’s generally used for prototyping and low-to-medium volume production. CNC cutting can also be used for these applications, but CNC equipment is faster and, therefore, better suited for higher-volume production.
Which Cutting Method is Better for Rubber Parts?
When choosing a cutting method for rubber products, it’s important to consider the thickness of the material, the complexity of the cut, the production volume, and whether the material is a sheet or an extrusion. Keep these general guidelines in mind.
- CNC cutting is generally a better choice for cutting flat, simple parts in high volumes where heat and material deformation from the cutting process aren’t concerns.
- Water jet cutting is generally a better choice for cutting more intricate parts, including extrusions, in low-to-medium volumes when heat and deformation are concerns.
Elasto Proxy can help you select the best cutting method for your project and operates flatbed or gantry-style water jet equipment at our manufacturing facilities near Montreal, Canada and in Simpsonville, South Carolina (USA). At our Montreal-area facility, we also have a multi-axis robot that can be used for abrasive water jet cutting.
