Repair 7

Mandrel-bent tubing describes a process that puts curves and angles in thin-wall tubes or pipes. Mandrel bending requires large press-like machines that have guides and cones to curve tubes and pipes at precise angles, and are used primarily for exhaust systems on gas- and diesel-powered vehicles of any size, as well as motorcycles and many smaller engines. Mandrel-bending machines also come in smaller, manual versions that are portable. Mandrel bending has become an alternative to standard bending processes, because of its faster and more efficient process.

Mandrel Tube Bending Machines

Mandrel tube bending machines come in small manual models or large industrial versions. The manual versions consist of a bed upon which the pipe or tube is placed, and then cinched down within a curved guide. Pulling a handle bends the pipe over an angled chock to the desired bend, such as 45, 90, or 180 degrees. Large industrial mandrel-bending machines use electricity to run hydraulic servos, where the operation is done automatically. The electric mandrel benders can be programmed for bend distances and angles. They come equipped with auto-loaders to feed the pipe, and head shifters to change the bend at any location on the pipe or tube.

Tubing and Pipes

Common tubes and pipes used in the mandrel-bending process include a large market in the automotive industry, which requires all manner of exhaust pipes, chassis frames and roll bars. Industrial applications require special bent tubes and pipes for free-flow gases and liquid conduits. Copper, steel, stainless steel, galvanized, titanium and other alloy-constructed pipes and tubes that have thin-wall construction provide the best material for the mandrel-bending process. The tube and pipe diameters can range from one to four inches, or more.

Mandrel Bending Advantages

Mandrel bending, as opposed to standard bending techniques, do not crush the pipe during the bending process. Therefore, the inside surface diameter is not lessened or closed off, which can create back pressure. Mandrel bending ensures a complete, unrestricted flow with no serrations or metal deformity. Mandrel bending can increase flow up to 35 percent in systems that require numerous sharp bends and custom patterns. Mandrel bending can increase exhaust flow in automotive vehicles, adding to horsepower and torque.

Customization

Mandrel bending can be customized for intricate angle patterns that require one-piece designs, eliminating the need for sectioning and the purchase of kits that have numerous assembly parts. Since the bend designs are programmed and kept in a computer database, in the case of the automated systems, the data can be recalled for producing multiple copies, or re-fabricating exact copies as replacement parts. Mandrel bending costs no more than standard bending, and takes less time and effort to fashion bends and patterns.

You may get a dent in your car hood if an object falls on it or you sat on the hood and it bent. You can save a trip to the garage and money by solving the problem at home. With a few basic tools, you can repair your bent car hood without the need of professional assistance.

Instructions

1

Assess the damage. If the car hood has completely buckled, you may not be able to fix it unless you are a mechanic. However, if the hood is bent from daily wear and tear (from sitting on it, for example), you can hammer out minor dents.

2

Remove the hood of your car. Unscrew it from the hinges, which are usually located underneath the front windscreen. Refer to the cars manual if you are unsure about how to do this because each model of car is different. Get a friend to help because the hood may be heavy.

3

Place the hood upside down on the grass or an old piece of carpet to prevent scratching the paint while you repair the hood.

4

Use the hammer to knock the dents out of the car hood. Strike the hood with firm, steady hits directly on the bend or dent. Knock the dents out slowly. It is better to use several, gentler hits instead of one strong hit that may cause more damage to the hood.

5

Use the block of wood on areas with large dents. Place the wood on the area and hammer the wood, instead of directly hitting the car hood. The wooden block will spread the pressure out over a greater area and help fix the dent.

6

Repeat steps 4 and 5 until the bend has been removed or minimized to your satisfaction. Turn the hood over if you need to work at the bends from the opposite side.

7

Paint the damaged area, if necessary, with car paint that matches the original color of the car. Let it dry.

8

Replace the hood by screwing it back onto the hinges. Align the hood correctly with the grill so that it closes properly.