What Is a Pneumatic Bar Feeder?

Posted on Apr 17, 2021

The pneumatic bar feeder consists of the bed that supports the bar stocks, the bar pusher that delivers the short bars through the end toward the chuck of the lathe machine, the clamping element which holds the short bar in place, and also the adjusting system for the bar loading position.

Pneumatic Bar Feeders Overview

A pneumatic bar feeder, which is also known as a pneumatic bar feed or pneumatic bar loader, is an economical and versatile solution for CNC lathe machines to automatically load the bar stocks into the machine tools. In general, pneumatic bar feeders which connect to the headstock of the lathe machines are filled with short bars that will be supplied into the turning area, going through a large variety of machining operations. 

The bar feeder varies from simple to advanced versions which can support the unmanned turning processes of a modern turning center without any human supervision during an entire shift or more. One of the biggest advantages of using a pneumatic bar feeder is to remove the need for loading the bar manually and monitoring the machining process in machine tools. Also, the actual productivity of the machining manufacturing processes can be significantly enhanced because of the unmanned material feeding. 

Typically, all sorts of bar feeders are available to constantly deliver and supply bar materials in different shapes like round, square, hex, or extruded shapes for CNC turning machines. Since there are numerous kinds of automatic bar feeders which have different feed capacity and size to support feeding bars with different diameters, so the users should identify the right pneumatic bar feeder that is best suited to the manufacturing requirements and the CNC turning center. Except for pneumatic bar feeders, hydraulic bar feeders are also commonly used for automatic bar feeding. 

Hydraulic bar feeders can be divided into 2 subtypes: the hydrostatic type of hydrodynamic type. Fluids, which refers to the oil in bar feeders in hydrostatic systems, just support the material loading process. The fluids are at rest but may exert a force when putting them under pressure. On the other hand, in a hydrodynamic system, the pressurized oil in the channels which clamp the top and bottom portion of the materials to hold them is in motion and can move the bars through the tubes. The hydrodynamic bar feeder is better suitable for applications that have faster spindle speed, but the change-over-time of different diameters increases in this case.

Basic Structure of Pneumatic Bar Feeders

The pneumatic bar feeder consists of the bed that supports the bar stocks, the bar pusher that delivers the short bars through the end toward the chuck of the lathe machine, the clamping element which holds the short bar in place, and also the adjusting system for the bar loading position.

Bar Feed Bed

The bed part of a pneumatic bar feeder is actually not fully flat. Instead, it is typically produced curved, angled, or circulated. With the design, the bar materials can rest at the bottom of the feeder bed, being ready for feeding into the lathe machines. Some pneumatic bar feeders employ rollers or other conveying devices to smoothen the bar loading operations.

Bar Pusher

The bar pusher in the pneumatic bar feeder is driven by a pneumatic system while in other kinds of automatic bar feeders, it may be controlled by a servo motor with a push rod or a hydraulic system. Using a pneumatic bar pusher, the moving part is driven by compressed air to push the short bars until they reach a turret stop. On the other hand, the bar pusher which is driven by the servo motor allows the user to regulate the amounts of materials and bar-type for the coming turning process and the bar loading distance through the spindles of the attached lathe machines. 

Comparing the two types, the pneumatic system, and the servo motor type, the pneumatic bar pusher delivers and positions the raw materials less accurately than the other type and may lead to material waste, however, it is more economical and simpler. The types of materials and the costs can determine which power source type is more ideally suited to the users' bar feeding applications.

Clamping Element and Adjustment

Clamping devices can effectively reduce vibrations and prevent any movement from happening. They are required in pneumatic bar feeders in order to grip firmly the rod, ensuring accuracy and stability. The short bars are required to line up at the center of the hole of the chucks all the time. As a result, the adjusting mechanism which checks the position of the materials in the system is also essential in the pneumatic bar feeders.

:: Read More: Why Are CNC Bar Feeders So Popular?

Feeding Capacity of Pneumatic Bar Feeder

There are a broad variety of bar feeders in the market, which are respectively suitable for different turning machines and machining production lines and material types. The length or the size of the pneumatic bar feeders is the vital factor when selecting the right bar feeder. In general, the maximum length of available bars of an automatic bar feeder is determined by machine headstock. For short bar version pneumatic bar feeders, they are typically used for bar lengths ranging from 120 to 150 cm. Some larger bar feeders can serve for a bar length of 360 cm or longer bars (12 feet). 

During the machining processes which have longer run time like the shifts lasting 8 hours or more, the capacity of a 12-foot magazine bar feeder is greatly ideal for high volume production. These automatic bar feeders grip multiple bars in reserve while the general bar feeders with only one tube holder can only hold 12-foot bars. After identifying the bar length and the capacity when selecting the pneumatic bar feeders, the room the devices take-up is also an important factor for users to consider.

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