Whether it’s a roaring truck engine or speeding Ski-doo cutting through fresh powder, you can bet vibration plays an important role when it comes to designing and manufacturing parts for medium/heavy truck or off-highway vehicle applications. What you might not know is that rubber hoses play an essential role in absorbing vibration. What’s more, you’re probably not familiar with the anatomy of a hose, how they’re manufactured or the market and demand for applications.
The world of rubber hoses is a fascinating and impressive one. It’s remarkable not only because of the varieties of hoses — from extruded and formed hoses to homogeneous hoses and reinforced hoses — but because of the wide-ranging industries where rubber hoses end up: in air brake systems for automotive applications, aerospace applications, motorcycles, and more.
So let’s take a closer look. From formed hoses for turbochargers to hose assemblies, you might be shocked to learn something new about rubber hose manufacturing.
Overview of Hoses: Three Layers of Hoses
While many varieties and applications for rubber hoses exist, all hoses perform one essential function: to transmit fluid or gas. When it comes to rubber hose anatomy, most are comprised of three layers. The first, an innermost “tube”— which is formed when rubber is forced through a profile to render a particular size — serves two purposes: to contain the fluid being conveyed and to resist being broken down by that fluid.
The second layer is a reinforcement known as the carcass. If the contained fluid experiences any sudden increases in pressure, the tube may require a fabric or wire carcass reinforcement. This ensures the tube is protected from internal pressure and outside forces. Carcass reinforcement wire is applied by braiding, knitting, spiraling, wrapping or weaving.
The third and outermost layer is the “cover.” The cover provides additional tube protection from external damage and environmental deterioration, such as from the ozone. The cover can be color-coded to aid identification or improve aesthetics. Though both reinforcement and a cover are commonly used, “homogeneous” hoses with no added layers are available.
While the inner lining protects the reinforcement layer from deterioration due to internal forces, the outer cover’s primary purpose is to protect the reinforcement layer from any damage due to external forces. The lining and cover are manufactured from various types of rubber including natural, styrene butadiene (SBR), nitrile, butyl and EPDM. Typical reinforcement materials include cotton rayon, polyester, nylon, aramid fibers and steel wire.
Rubber Hose Manufacturing
When it comes to manufacturing, rubber hoses can be produced in several methods, including extrusion, spiral wrapping, calendaring, hand layup and molding. In general, small diameter hoses are primarily produced through extrusion, while larger diameter rubber hoses are typically created through spiral wrapping.
The Rubber Hose Industry
Now that we understand the anatomy of rubber hoses let’s explore the rubber hose segment of the industrial rubber product industry, which encompasses vehicular, fluid power, water, air and other industrial types.
Vehicle hoses are and will continue to be, the largest segment, accounting for over one-third of total hose demand. Increases in vehicle production as well as an increase in the total number of vehicles in use drive demand in the OEM and replacement markets, respectively. Higher-valued, customized hoses designed to function in environmentally harsh, under-the-hood applications also support demand.
Rubber Hose Markets
Rubber hoses are used in a wide variety of durable goods sectors including industrial machinery, motor vehicles, aerospace equipment and other transportation equipment. Almost two-thirds of total rubber hose demand is attributable to industrial equipment, including off-road equipment such as construction and agricultural equipment. Virtually every category of hose is utilized in industrial equipment, with fluid power, industrial and vehicular hoses being especially prevalent. The motor vehicle industry is also a large consumer of rubber hoses for engines, transmissions, steering, air conditioning and braking systems.
Applications for Rubber Hoses
With an understanding of rubber hoses, manufacturing, the industry, as well as the markets and demand, let’s now turn our attention to applications for rubber hoses. Because they are flexible and can absorb vibration, rubber hoses are suited for designs that move and shake. High-pressure hydraulic applications often use hoses to contain water-oil and water-glycol mixtures and low viscosity mineral oils.
Automotive air brake systems often include rubber hoses with an oil and grease resistant tube made of nitrile (NBR), chloroprene or a blend of NBR and styrene butadiene (SBR), Reinforcement is typically a synthetic textile yarn with high tensile strength. The cover may be CR, SBR, or chlorosulfonated polyethylene (CSM).=
Automotive fuel hoses generally feature oil-resistant tubes of NBR, sometimes compounded with polyvinyl chloride or PVC. As with airbrake hoses, reinforcement is often textile yarn made of polyester, polyamide or rayon. Some fuel hoses don’t have a cover; when one is added, it commonly made of oil-resistant CR or CSM. Because fuel lines can be immersed inside the fuel tank, it may be necessary that the cover be as fuel-resistant as the tube.
Radiator coolant hoses can be factory-molded into curves to fit specific spaces. Ethylene propylene (EPDM) is the typical tube material because of its strong resistance to heat, hot water, and ethylene glycol, the most common antifreeze. In some cases, SBR or NBR may be used instead. Fiber or textile reinforcement may be applied, and the cover may be EPDM, SBR, or CR.
Other uses include liquid propane (L.P.) gas hose, Freon charging hose, air hose, oxygen hose, acetylene hose, water hose, steam hose, washing machine hose and gas pump hose.
Example Applications for Formed Rubber Hoses
Now that we’ve provided an overview of applications for rubber hoses let’s and drill down and talk more specifically about radiator hoses and fuel filler hoses — two major types of formed rubber hoses in which we specialize.
A Closer Look at Radiator Hoses
The coolant system hoses we offer are manufactured per the SAE J20 surface vehicle standard, types 20 R 3 and 20 R 4 — heater and radiator hoses for normal service. Within each type of coolant system hose, various classes are further defined based on differing resistance to variables such as temperature and oil. For example, our 20 R 4 hoses are class D-1 and are made of an ethylene propylene (EPDM) compound. As you may already know, EPDM is the primary polymer used for coolant hoses because of its excellent resistance to heat, hot water and ethylene glycol. EPDM also has good resistance to weathering and ozone damage. When it comes to manufacturing radiator hoses, the inner liner (of EPDM) is extruded first, then this “tube” is reinforced by a layer of knitted fabric (such as polyester, rayon or Kevlar) and covered by an outer layer of EPDM. Next, the hose is cooled in water and cut into lengths. These lengths are placed on shaped metal mandrels. During vulcanization in high-pressure steam, the hoses assume the shapes of the mandrels.
Fuel Filler Hoses: What You Need To Know
Besides radiator hoses, we also provide fuel filler hoses manufactured per the SAE J30 surface vehicle standard, types 30 R 6 and 30 R 7 — low-pressure hoses for use with gasoline, diesel fuel, lubrication oil, or fuel system and crankcase vapors found in internal combustion engines.
Our 30 R 6 rubber hoses feature a smooth inner tube made of fuel and oil resistant synthetic rubber (such as nitrile) reinforced (by polyester, rayon or kevlar) and covered with an oil-, ozone-, and heat-resistant synthetic rubber such as chloroprene. They are designed to connect the vehicle filler neck to the fuel tank and to resist gasoline, diesel fuel, gasohol and oxygenated fuels.
As you can see, the world of rubber hoses is an impressive one. And that’s just the tip of the rubber and plastic iceberg. Whether it’s rapid manufacturing for plastic injection molded parts or quick turnaround time rubber parts, leading names turn to us not only for our parts but for our partnership, as well.