Fixturing is one of the basic systems in CNC production. Tools and details are fixed in holders. There are many types of clamps for CNC machines. However, their selection for CNC machining must meet production requirements. In case of choosing the wrong holder, the machined object and tool can be damaged by vibrations, a broken end of the device, loosely attached material, etc. All these factors can cause errors in machined products. This article discusses tips for choosing a holder for CNC machining based on production requirements.
CNC Clamps - Guide to Choosing the Right Type of Holder for Machining
The method of securing CNC machining should be selected according to production requirements. Typically, the cutting process takes place in batches. Products can have simple or complex structures and depending on these factors, the inclination of the tool, the orientation of the machined object, etc. may vary. The securing during CNC machining also affects the development time of the detail and the total production time (including preparation and waiting). Here are some tips on how to choose the right type of CNC securing system for low and high volume CNC fabrication.
Choosing CNC devices for low-volume production
Generally speaking, combined fixtures are suitable for small-scale production. Below we explain what to choose when not operating on a large scale.
Block/Combined Clamps
This is a unified clamp system. It has a construction block with multiple sockets for connecting various CNC machining tools. It is equipped with a universal, standard design and can be adapted to various CNC cutting devices. In small-scale CNC processes, this type of tool holders are suitable, as they shorten the total production cycle time. The blocks can be rotated to match specific CNC sub-assemblies to the workpiece, positively affecting tool changeover times. This makes these combined holders ideal for hassle-free CNC machining. Combined clamps can have two additional elements, listed below.
Precision Pliers:
These are assembly parts in a combination device that help align tools in the device. It is recommended to use them when the clamping force exceeds 5000 Kgf. They prevent the tool body from being damaged by the fastening forces.
Clamp:
The holder is a platform between the positioning surface and the workpiece. It is used for precise positioning of the material to ensure the proper interaction of the tool with it during the CNC process.
CNC clamps for mass production
Mass production has longer waiting times, longer execution times, and retooling times. To shorten the overall scope of production, hydraulic or pneumatic holders are used.
Hydraulic/Pneumatic Clamps
This is a special type of clamp used for securely holding tools during long production runs. These holders utilize hydraulic or pneumatic energy as the power source for the fastening tool. They can withstand greater cutting forces and achieve high positioning accuracy of the device and the workpiece. Electric grippers with permanent magnets are suitable for both types of CNC production cycles.
Electric clamp with permanent magnet
These are magnetic clamps that can be ready to hold tools within 1 second. These holders shorten the clamping time, and thus the entire production time, and are also suitable for small and large scale production with a holding force not less than 450 Kgf. Selecting equipment for CNC machining is a task for the CNC machine operators. Operators should be trained to make the right choice. However, clamps come in various forms and formats. Let's take a look at different types and assess how to choose the right type for a specific application.
Types of Clamps
First, let's quickly go through the different types of fasteners for a basic CNC machine with a T-slot frame:
1. Wood Screws
Using wood screws to hold objects to spoilers is not something very complicated. On the contrary, it is one of the basic fixtures for CNC machines and additionally relatively easy to assemble. Although it is sturdy, safe, and provides a solid grip point, it can damage the spoiler's finish.
2. Double-sided tape
The double-sided tape method is another simple way to secure details. In this case, cover the storage base with double-sided tape and stick the other side to the work surface. Remember, this method will only work if you use high-quality tape and it may not work with some materials.
3. Articulated Clamps
Cross clamps provide the fastest system for holding and releasing material of the same thickness. They are easy to use and convenient, but have limited scalability, as height is the main issue during adjustment.
4. Step Blocks
Step blocks require an additional working area with a T-slot or a grid with threaded inserts. However, this extra equipment provides greater safety, while overcoming the problem of hinge clamp adjustment. The only possible downside of this grip is that it cannot be surface machined.
5. Eccentric clamps
Eccentric clamps use lateral force to hold the material in place and secure it to the work area. This allows you to hold the workpiece without placing anything on the magazine, making it easier to reach the surface. However, they require T-slots or grates with threaded inserts, which can be a major disadvantage for some.
6. Vacuum Clamps
Vacuum grippers or vacuum pads provide great versatility in securing items on CNC machines. They can be attached anywhere in the work area, and a vacuum pump will hold the processed object in place, drawing it into place. They are easy to use, quick to clamp and release, and require minimal setup time. Therefore, the cost of such systems is often a serious obstacle.
Summary
The selection of equipment affects the efficiency of CNC machining. Operators must be trained in the intricacies of tightening, different types of tightening, and when to use what. By utilizing this knowledge to supplement CNC machine tool production, operators help increase productivity, accuracy, and safety of operations.