Bulkhead Tank Fitings - Rotaloc Int'l, LLC - Post Applied Bulkhead Fittings

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Bulkhead Tank fittings

Rotaloc® Bulkhead Tank fittings We carry all SAE & NPT standard bulkhead tank fittings sizes. Products are available with double or single ports, partial or complete assemblies, stainless steel, brass or aluminum. Custom sizes and mold-in options available as well. Let us know what we can do to assist with your next order! We also can assist with customization of these fittings, available upon request.

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Molding Processes
(Five common molding processes)

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Rotational Molding (Rotomolding)

Rotational molding is a highly versatile manufacturing option that allows for unlimited design possibilities with the added benefit of low production costs.

Process Overview

The rotational molding process starts with a good quality mold that is placed in a molding machine that has a loading, heating, and cooling area.

Several molds may be placed on the machine at the same time. Pre-measured plastic resin is loaded into each mold, and then the molds are moved into the oven where they are slowly rotated on both the vertical and horizontal axis. The melting resin sticks to the hot mold and coats every surface evenly. The mold continues to rotate during the cooling cycle so the parts retain an even wall thickness.

Once the parts are cooled, they are released from the mold. The rotational speed, heating and cooling times are all controlled throughout the process.

Design Advantages

Rotational molding offers design advantages over other molding processes. With proper design, parts that are assembled from several pieces can be molded as one part, eliminating expensive fabrication costs.

The process also has a number of inherent design strengths, such as consistent wall thickness and strong outside corners that are virtually stress free. If additional strength is required, reinforcing ribs can be designed into the part.

Rotational molding delivers the product the designer envisions. Designers can select the best material for their application, including materials that meet FDA requirements. Additives to help make the part weather resistant, flame retardant, or static free can be specified.

Inserts, threads, handles, minor undercuts, flat surfaces that eliminate draft angles or fine surface detail can all be part of the design. Designers also have the option of multi-wall molding that can be either hollow or foam filled.

Cost Advantages

When cost is a factor, rotational molding has the advantage over other types of processes as well. In comparison to injection and blow molding, rotational molding can easily produce large and small parts in a cost effective manner. Tooling is less expensive because there's no internal core to manufacture. Since there is no internal core, minor changes can be easily made to an existing mold.

And because parts are formed with heat and rotation, rather than pressure, molds don't need to be engineered to withstand the high pressure of injection molding.

Production costs for product conversions are reduced because lightweight plastics replace heavier, often more costly materials. Which makes rotational molding as cost effective for one-of-a-kind prototypes as it is for large production runs.

~ Association of Rotational Molders

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Injection Molding

What is Injection Molding?

Injection molding is a manufacturing process widely used for producing items from toys and plastic trinkets to automotive body panels, water bottles and cell phone cases. A liquid plastic is forced into a mold and cures - it sounds simple, but is a complex process. The liquids used vary from hot glass to a variety of plastics - thermosetting and thermoplastic.

History

The first injection molding machine was patented in 1872, and celluloid was used to produce simple everyday items such as hair combs. Just after the Second World War, a much improved injection molding process - 'screw injection' was developed and is the most widely used technique today. Its inventor, James Watson Hendry, later developed 'blow molding' which is used for example to produce modern plastic bottles.

Types of plastic

The plastics used in injection molding are polymers - chemicals - either thermosetting or thermoplastic. Thermosetting plastics are set by the application of heat or through a catalytic reaction. Once cured, they cannot be remelted and re-used - the curing process is chemical and irreversible. Thermoplastics, however, can be heated, melted and re-used.

Thermosetting plastics include epoxy, polyester and phenolic resins, whilst thermoplastics include nylon and polyethylene. There are almost twenty thousand plastic compounds available for injection molding, which means that there is a perfect solution for almost any molding requirement.

Glass is not a polymer, and so it does not fit the accepted definition of thermoplastic - though it can be melted and recycled.

The Mold

The making of molds has historically been a highly skilled craft ('die-making'). A mold is usually in two main assemblies clamped together in a press. Making a mold often requires complex design, multiple machine operations and a high degree of skill. The tool is usually steel or beryllium copper which is used for mold making requires heat treatment to harden it. Aluminium is cheaper and easier to machine, and may be use for shorter run production. Nowadays, computer controlled milling and spark erosion ('EDM') techniques have enabled a high degree of the automation of the process of mold manufacturing.

Some molds are designed to produce several related parts - for example a model aeroplane kit - and these are known as family molds. Other mold designs may have several copies ('impressions') of the same article produced in one 'shot' - that is, one injection of plastic into the mold.

How Injection Molding Works

There are three main units which make up an injection molding machine - the feed hopper, the heater barrel and the ram. The plastic in the hopper is in granular or powder form, though some materials such as silicone rubber may be a liquid and may not require heating.

Once in hot liquid form, the ram ('screw') forces the liquid into the tightly clamped mold and the liquid sets. More viscous molten plastics require higher pressures (and higher press loadings) to force the plastic into every crevice and corner. The plastic cools as the metal mold conducts heat away and then the press is cycled to remove the molding. However, for thermosetting plastics, the mold will be heated to set the plastic.

Advantages of Injection Molding

Injection molding enables complex shapes to be manufactured, some of which might be near impossible to produce economically by any other means.

The wide range of materials enables almost exact matching of the physical properties required from the article, and multi layer molding enables tailoring of mechanical properties and attractive visual appearance - even in a toothbrush

In volume, it is a low cost process, arguably with minimal environmental impact. There is litle scrap created in this process, and scrap that is produced, and be re-ground and re-used.

Disadvantages of Injection Molding

The investment in tooling - making the mold - typically requires high volume production to recover the investment, though this does depend on the particular article. Producing the tooling takes development time and some parts do not readily lend themselves to a practical mold design.

The Economics of Injection Molding

A high quality mold, although of relatively high cost, will be capable of turning out hundreds of thousands of 'impressions'. The plastic itself is quite inexpensive and despite the energy required to heat the plastic and cycle the press (to remove each impression) the process can be economic for even the most basic items such as bottle caps.

By Todd Johnson, About.com Guide

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Blow Molding

Blow molding is a process used in making hollow plastic parts. There are three main types of blow molding: injection blow molding, stretch blow molding, and extrusion blow molding. Each type is similar, but there are differences in the process for each, and each is better suited for a different need.

Blow molding has its advantages and disadvantages. The advantages of blow molding are:

      • Low cost for tools
      • Quick Production
      • Molding of complex parts
      • Produces parts that can be recycled

The drawbacks to blow molding are:
      • Limited to only making hollow parts
      • Hard to control the thickness of the walls

Production and Uses of Each Blow Molding Process

Injection Blow Molding

This process is used for making glass and plastic products, such as single serving bottles and small medical devices, in high volume. The polymer is injected on to what is called a core pin, which is then inflated, cooled, and ejected.

To begin with, the polymer is melted down and then fed into a manifold, which injects it into a hollow mold. This preform mold is what makes the outer shape. The internal shape is formed when the preform is clamped around a core rod, or mandrel. Then compressed air is pumped into the preform, inflating it into its final shape.

The mold is then allowed to cool before being removed from the core rod, which is known as ejection.

Stretch Blow Molding

This process begins with a preform being made as done in the injection method. The preforms are then heated up, usually with infrared heaters. Then it is blown with high pressure air using metal blow molds. The preform is stretched using a core rod. This process is generally used when making bottles, jars, and other containers.

Extrusion Blow Molding

This process sees plastic melted and extruded into a hollow tube called a parison. The parison is then enclosed in a cooled metal mold. Air is then pumped into the parison, causing it to take the desired shape. After a cooling period, the part can then be ejected from the mold.

Extrusion blow molding can be further broken down into two types: continuous extrusion and intermittent extrusion. In continuous extrusion blow molding, the parison is continuously extruded, with individual parts being cut out. With intermittent extrusion blow molding, a machine injects melted plastic into the parison part by part.

This process is used for making things like milk and dairy containers, shampoo bottles, and hollow industrial pieces.

History of Blow Molding

The idea behind blow molding comes from glass blowing. The first two people who are known to have used the blow molding process are Enoch Ferngren and William Kopitke. In 1938, they produced a blow molding machine, which they then sold to the Hartford Empire Company, kicking off the commercial use of blow molding.

Due to the lack of variety in products that could be produced, the process was not very popular for quite some time. As more and more products were able to be made from blow molding, however, its popularity increased.

A big boom to the industry came from soft drink bottles. In 1977, there were zero pieces produced for the soft drink industry through blow molding. In 1999, there were ten billion pieces blown for the soft drink industry. The number is substantially larger today, and is expected to continue increasing.

By Todd Johnson, About.com Guide
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Vacuum Forming

What Is Vacuum Forming

Vacuum forming is a process where sheets of plastic are heated to the point that they become pliable, allowing them to be formed around a plug or male mold. It is so simple, that people can actually take on smaller jobs, such as making masks for costuming, right from their home without the need for expensive equipment. There are, however, several uses for vacuum forming in a production environment using machinery to make heavier gauged vacuum formed plastic.

Examples of Industrial Items Made with Vacuum Forming

One of the reasons vacuum forming is so economical is because plastic is cheaper than some of the alternatives such as sheet metal, fiberglass, and plastic injection molding. Some examples of industrial items made with vacuum forming include:

      • Spa and hot tub shells
      • ATMs
      • Kiosks
      • Medical imaging device enclosures (such as for an MRI or CT machine)
      • Trim and seat components in various vehicles
      • Engine covers for motors that come into the cab of the vehicle such as in
        some vans and trucks

Issues with Vacuum Forming

For all of the benefits that come with vacuum forming plastic, there are a few issues with using it. The first common problem encountered with vacuum forming plastic is that it absorbs moisture, which in turn forms bubbles inside of the plastic. This is an issue, however, that is eliminated through extending the drying process.

Another issue encountered with vacuum forming is webbing around the mold. This is caused either by using too large of a mold, having parts of a mold too close together, or overheating of the plastic. Again, these are all issues that can be avoided.

The third issue that occurs with vacuum forming is that the final product often sticks to the mold. This, again, can be avoided. There simply needs to be an angle of three degrees or more.

Types of Molds used in Vacuum Forming

There are four different types of molds used in vacuum forming, each with its own unique characteristics, and sometimes are used in concert with one another for projects. Let’s have a look at each type.

Wood patterns are usually used in the first stage of a vacuum forming project. The first advantage to this type of mold is that they are fairly inexpensive. Additionally, they make it very easy to make design changes. Wood patterns are almost always used to gauge how the part is going to come out before getting started with full production. Once everything is up to snuff, the wood pattern is then used to make either a ceramic composite mold or a cast aluminum mold for full-scale production.

Cast aluminum molds, which are cast in a foundry, have what is known as temperature control lines running through them. This helps in the forming process with regulating the heat being put on the product, as well as actually making the process much faster. They are also very versatile in terms of types of materials that can be produced. The only real drawback to using these types of molds is that they are fairly expensive.

Machined aluminum molds are the same as cast aluminum molds with the exception of how they are made. They are cut from a solid piece of aluminum using some sort of machine and program, such as CAD or a CNC machine. These are generally used for lighter gauge materials or very shallow pieces. Like cast aluminum molds, these are very expensive to make.

Composite molds are the low cost options out there when compared with aluminum molds. Composite molds are generally made from a thermoset resin that started as a liquid before hardening. Composite molds do have quite a bit of usage lifetime associated with them, with ceramic molds being the longest living type of composite mold. They are a popular choice because they are significantly less expensive than aluminum, and work for all but the largest volumes of production.

By Todd Johnson, About.com Guide

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Plastic Extrusion

Plastic extrusion is a process where plastic is melted and formed into a continuous form. This process is used for producing things such as pipe, fencing, tubing, wire insulation, window frames, and railing, to name a few.

The Basic Process of Plastic Extrusion

The process uses plastic resin, which are small plastic beads, fed through a hopper into the extruder's heated barrel. There, a rotating screw, which generally turns at 120 rpm, pushes the resin through the barrel as it is generally melted at anywhere from 392 degrees to 527 degrees Fahrenheit, depending on the polymer the resin is made up of. To help reduce the risk of overheating the resin, the heat is gradually increased from one side of the barrel to the other.

At the front of the barrel, there is a screen that the melted resin is pushed through to help filter out anything that may have contaminated the resin. Once the melted thermoplastic resin passes through the screen, a feed tube sends the resin through a shaped die, which then gives the product its profile. This shape or profile, can be made continuously, at any length.

Finally, the product must be cooled. This is usually done by means of a water bath. Plastic holds heat well, so the cooling process takes some time. Because of this, the water bath is often sealed and a vacuum is used to keep the product from losing its shape while it cools.

Types of Plastic Extrusion

There are variations to the extrusion process depending upon what type of extrusion is being performed. Here is a look at the different types of extrusion, and the differences from the basic process for each.

Sheet Extrusion

Sheet extrusion, also known as film extrusion, is used for making plastic sheeting and films, and it generally varies from the basic extrusion process in regards to the cooling process. Rather than using a water bath to cool the finished product, the sheets are cooled by being pulled through a series of three to four pinch rollers. In addition to cooling the product, the rollers are also used to determine the thickness of the final product.

Blown Film Extrusion

Blown film extrusion is used for making products such as plastic shopping bags. The process is the same as the basic extrusion process up until the point of the resin going into the die. The die is an upright cylinder with a circular opening. The melted resin is pulled upwards from the die by a pair of nip rolls high above the die. Changing the speed of these nip rollers will change the thickness of the plastic film. Around the die sits an airflow based cooling ring, which cools the product as it travels upwards. Air is blown into the die, expanding the extruded product. This film can then be spooled or printed on, cut into shapes, or heat-sealed into other products.

Tubing Extrusion

Tubing extrusion is used to make products such as straws or medical tubing. The process is the same as the basic process up until the resin reaches the die. A pin (mandrel) is placed inside of the die. The melted resin is then pushed into the die, forming around the mandrel. This is how the hollow shape of the tubing are formed. Air pressure is used to gauge the thickness of the tubing.

These are just a few of the process used for plastic extrusion. The biggest advantage to all of these forms of the plastic extrusion process is that they give a wide range of geometric possibilities over other forms of plastic form production. The differences in shapes and sizes that can be produced is vast, with the only limitation being that the product must have a continuous profile.

By Todd Johnson, About.com Guide
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	About Custom Components We have the manufacturing capabilities to design and customize almost anything imaginable. Some of our capabilities include Turning, Bending, Stamping, Castng, Forging, Laser Cutting, CNC machining, EDM, Molding, Welding, fabrication, assembly and much more. Below are brief descriptions of the shown products and how they are applied in their prospective industry:
	Image 1 - Turned Fitting This custom Hosebarb fitting is turned, bored, machined and polished out of Stainless Steel.
	Image 2 - Finishing bolt This Custom Bolt and Square Sleeve was produced for a prototype furniture design out of Mild Steel.
	Image 3 - Custom Bushing A custom linear-knurled press-fit insert.
	Image 4 - Deck Fastener Anodized Aluminum Boat Deck-Fitting.
	Image 5 - "What is this?" Custom Threaded Insert produced by turning, stamping, machining, drilling & Tapping. Stainless Steel
	Image 6 - Multibase - Custom Ring Custom Multiring produced out of Aluminum using Loss-Wax casting.
	Image 7 - Custom Press Fit Insert This insert is produced from Brass and press-fit into a steel baseplate to increase pull-out strength.
	Image 8 - Triple Hex A large-thread triple Hex insert.

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Bulkhead Tank fittings

Rotaloc® Bulkhead Tank fittings