Flexible Metal Hose is manufactured via two possible processes, mechanically formed and hydraulically formed. This means they are either formed by means of shape altering tools or via hydraulic deformation. Each process employed by United Flexible has different sub-methods to achieve their goal.

Mechanical Forming

Inward Corrugating

This is also referred to as die forming. This method consists of a series of rotating dies that close and “neck down” the tubing been fed to it and then sequentially opened up again to continue the process. The secondary part of the process are additional dies that rounds the corrugation to its final pitch and defines the distance between the corrugations.

Some of the advantages of this process is a consistent inside and outside dimension, with precise tolerances; desirable residual cycles lives and no need for internal cleaning after manufacturing.

Outward Corrugating

This is also referred to as elastomeric forming. The basis of this method is an elastomeric donut that fits between two compressing surfaces with a mandrel feeding the tube inside. As the two compressing surfaces come together, the elastomeric donut expands radially. This action pushes the thin wall of the hose outwardly with a consistent process. As with inwardly corrugating, a secondary part of the process are additional dies that rounds the corrugation to its final pitch and defines the distance between the corrugations.

An advantage of this process is that is best suited for large diameter hoses, where consistent design and performance are required. While the processing speed is slow, this does allow for fine tuning if required during corrugating.

Hydraulic Forming

Water Forming

This form of hydroforming is the most commonly used throughout the industry. Although water is an incompressible fluid, it is utilized with air to pressure the inside of the tube.

There are two other ingredients to the mix, namely, the outer dies and the mandrel. The outer dies are a series of thin bladed forms that form the outline of the outside of the hose. These dies are held in place to form the corrugations of the hose wall. When the pressure is held at a constant pressure, the forms move together to form the final internal and external diameters of the hose.

The advantages of this method provide for a consistent shape and pitch, however, it is limited to thin-walled hose flexible hoses. Otherwise, the water pressure would be unable to deform the thicker hose wall material, which would allow for high working pressures. The hose also needs to be dried to remove water residual.

Oil Forming

This is similar method to hydroforming but is used when extra high pressures are required for heavier wall thicknesses. No air is injected into the oil, which is the primary forming media. Water soluble oils may be used for cleanliness purposes.

All of these processes of utilized in the forming of United Flexible’s Metal Hose Products that are offered today.

Please contact our factory if you have any further questions!