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Rotational molding Machines
Aug 29, 2017

Rock and roll machine[edit]

Picture of a Rock and Roll rotational moulding machine at an inclination of 45 degrees

A Rock and Roll rotational molding machine built in 2009

This is a specialized machine designed mainly to produce long narrow parts. Some are of the clamshell type, thus one arm, but there are also shuttle-type Rock & Roll machines, with two arms. Each arm rotates or rolls the mold 360 degrees in one direction and at the same time tips and rocks the mold 45 degrees above or below horizontal in the other direction. Newer machines use forced hot air to heat the mold. These machines are best for large parts that have a large length-to-width ratio. Because of the smaller heating chambers, there is a saving in heating costs compared to bi-axial machines.[4]

Clamshell machine[edit]

This is a single arm rotational molding machine. The arm is usually supported by other arms on both ends. The clamshell machine heats and cools the mold in the same chamber. It takes up less space than equivalent shuttle and swing arm rotational molders. It is low in cost compared to the size of products made. It is available in smaller scales for schools interested in prototyping and for high quality models. More than one mold can be attached to the single arm.[5]

Vertical or up & over rotational machine[edit]

The loading and unloading area is at the front of the machine between the heating and cooling areas. These machines vary in size between small to medium compared to other rotational machines. Vertical rotational molding machines are energy efficient due to their compact heating and cooling chambers. These machines have the same (or similar) capabilities as the horizontal carousel multi-arm machines, but take up much less space.[6]

Shuttle machine[edit]

Most shuttle machines have two arms that move the molds back and forth between the heating chamber and cooling station. The arms are independent of each other and they turn the molds bi-axially. In some cases, the shuttle machine has only one arm. This machine moves the mold in a linear direction in and out of heating and cooling chambers. It is low in cost for the size of product produced and the footprint is kept to a minimum compared to other types of machines. It is also available in smaller scale for schools and prototyping.[5]

Swing arm machine[edit]

The swing-arm machine can have up to four arms, with a bi-axial movement. Each arm is independent from each other as it is not necessary to operate all arms at the same time. Each arm is mounted on a corner of the oven and it swings in and out of the oven. On some swing-arm machines, a pair of arms is mounted on the same corner, thus a four-arm machine has two pivot points. These machines are very useful for companies that have long cooling cycles or require a lot of time to demold parts, compared to the cook time. It is a lot easier to schedule maintenance work or try to run a new mold without interrupting production on the other arms of the machine.

Carousel machine[edit]

Picture of a Carousel machine with 4 independent arm

A Carousel machine with four independent arms

This is one of the most common bi-axial machines in the industry. It can have up to 4 arms and six stations and it comes in a wide range of sizes. The machine comes in two different models, fixed and independent. A fixed-arm carousel consists of 3 fixed arms that must move together. One arm will be in the heating chamber while the other is in the cooling chamber and the other in the loading/reloading area. The fixed-arm carousel works well when working with identical cycle times on each arm. The independent-arm carousel machine is available with 3 or 4 arms that can move separately from the other. This allows for different size molds, with different cycle times and thickness needs.[6]