The Best Bender: The Electric Tube Bender

Posted on Dec 31, 2020

electric tube bender

A truly all-electric bending machine uses electric servo drives to close and align dies and perform bending operations. There may be some minor functions, such as collet closure or pipe supports, which are pneumatic, but the main functions that control the setting and operation of the tooling are always electrically driven.

Electric Tube Bender

There are many types of tube benders on the market today, including an electric tube bender, and there are many factors to consider when choosing. Some buyers will look ahead and buy more capacity or more for future use, so this could potentially influence your decision. For most companies, the final decision point usually ends as: "Choose the best machine that will do the job with the lowest investment cost"

Of course, factors such as operator skill level, energy consumption, footprint and layout, part process flow, quality, and accuracy of part shapes should be considered, but generally, the three main factors are:

1. Application limitations:

What are the minimum / maximum tube size, part shapes, and material types?

2. Quantitative considerations:

How many parts are to be produced? How many hours a day will the machine work? How many times per day or week do the tooling change?

3. Budget constraints:

How much can be spent on the project and what will be the return?
Before we dive into the breakdown of these three main factors, consider the type of machines on the market today.

:: Read more: The Awesome CNC Tube Bending Machine

Types of Pipe Benders

Pipe benders are similar to tube benders but are used in different applications. Do not use a pipe bender on tubes and vice versa. Here are some types of pipe benders:

● Single semi-automatic axle:

This type of pipe bender is the cheapest and is effective for single bend parts or simple multi-plane parts with low volume. The only controlled axis of this type of bending machine is the bending angle. Straight length and rotation are set by the operator.

● CNC - Single Stack:

This pipe bender can control the bending angle, pipe rotation, and straight length. This is called a "single stack" because it only allows one set of tools to be mounted at a time. This pipe bender is the basis of a CNC tube bending machine which is able to produce moderate to high volume parts.

● Double head:

As the name suggests, this machine has two bending heads and uses a compression bending process to wrap the tube around the die. Must not bend small radius parts with mandrels. It is a very fast bending machine whose main application is symmetrical, high-volume shapes with lower bending factors. Products such as shopping carts, furniture, wheel bushing frame, lawn mower parts, etc.

Types of Bender Drive Systems

See below for some of the drive systems for tube and pipe benders:

● Hydraulic:

It uses a hydraulic power system to close the dies and rotate the bending die. In today's production environment, these tube benders are usually less expensive machines that are reliable but also have limitations on speed and accuracy.

● Hybrid - Hydraulic / Electric:

It uses a hydraulic system for some functions such as die closing and mandrel extraction, but the bending die drive is an electric servo. This gives the machine higher productivity and better control of bending accuracy at higher speeds. The brand hybrid benders use hydraulic actuators for closing the dies which are automatically positioned and therefore provide a system comparable to all-electric.

● Hybrid – Pneumatic/Electric:

Some manufacturers build machines that use air actuators to close the dies, and there may even be electric servos for positioning the dies. These machines are often referred to as "electric" tube benders but are not all-electric. The only reason to do this is to cut costs and provide higher margins to machine builders.

● Everything electric:

A truly all-electric bending machine uses electric servo drives to close and align dies and perform bending operations. There may be some minor functions, such as collet closure or pipe supports, which are pneumatic, but the main functions that control the setting and operation of the tooling are always electrically driven. This gives the machine a very consistent and very precise control of process variables without so much operator intervention.

The Direction of Rotation of the Machine

The standard tube bender will rotate left or right. This determination is made by looking down at the flexion ankle. If it rotates clockwise when bending, it is a right-hand machine. If it rotates counterclockwise, it is a left-handed machine.

Some pipe benders are designed to be bidirectional, which means they can change the bending direction on the fly from LH to RH. These machines can be very complex shapes, but can also have stiffness limits and are typically 40% more expensive than a uni-directional bender.

The reason for having different rotary machines is to avoid hitting the pipe against the machine, tooling, or the floor during the part forming process. A common rule of thumb is that 85% of parts can be formed in any direction, 10% can only be formed in one specific direction, and 5% of parts require both directions.

So between the types of benders, different styles of drive systems, and rotation direction, there are numerous choices in the marketplace. Below are charts that help to summarize the various choices.

Bender Drive Systems

There are so many different uses for bending that you could write an entire book on the subject and still not cover everything. For the purposes of this discussion, we will cover the basics of application analysis to determine which tube bending machines can be used to produce pipes of different shapes and meet quality and quantity requirements. The process includes the following steps:

1. Determine the correct size of the machine to fit the minimum / maximum pipe size. Some applications may require several-tube benders to cover the entire range. 

2. Review the material to be formed on the machine. A difficult alloy material will require significantly more torque and stiffness than mild carbon steel. The type and shape of the material will also have an impact on the type of gear that needs to be specified. Another issue is reducing the amount of waste generated at the pipe ends or during setup.

3. Review part shapes to make sure tubing will not collide with the machine or tooling. This will tell you if you need an LH or RH rotary machine, or maybe a double bending machine is best suited. A proper set of drawings with bending coordinates or having a reverse engineering sample is absolutely essential for this process.

4. Review any special requirements, general tolerances, wall ovality or thinning, or other quality requirements as these may require additional machine options.

5. Review the tooling requirements and determine what tools are needed to run the application and meet the quality requirements. Pay attention to the length of the handles between the bends and at the beginning and end of the pipe. Die marks are another problematic point to consider.

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