Our company make compression molded tooling, design and manufacture different kinds & construction of elastomeric silicone rubber syringe sleeve & cover, expansion joint & flexible boots, bellows suction cup, air bellows etc, which as a protective appliance to dust proof, anti-oil, water proof and other environment elements in aim to keep equipment performance in medical device, machine automotive, pumping, industrial usage etc.
Small Rubber Bellows
Small Rubber Bellows, also known as Miniature Rubber Bellow, Custom Rubber Bellows, Molded Rubber Bellows and Bellow Expansion Joint.
A silicone rubber bellow is a small part manufactured by a variety of elastomers, like silicone, NBR, EPDM, CR, Liquid silicone bellows, etc.
Custom Rubber Bellows are widely used for industrial purposes because it helps in multiple functions. First and foremost, rubber dust boot is used to protect the moving parts of an engine from dust and humidity. Moreover, its function includes the isolation of vibration and the release of pressure between the engine’s parts. In addition to these, a rubber bellow is often placed to correct the position of misaligned parts within a piece of machinery. Lastly, it has found plenty of functions where sealing is essential.
Small Rubber Bellows Main Materials
Small Rubber Bellows/ Miniature Rubber Bellows can be made from a variety of materials. The material choice is based on the nature of the material handled, temperature, pressure, and frequency of operation. Elastomeric Molded Rubber Bellows materials are highly resistant to chemicals at high temperatures. However, the mechanical properties of elastomeric materials will be weakened at a higher temperature (above 150°F). The most used materials for the production of rubber bellows are the following:
Natural Rubber (NR)
Silicone Rubber: common silicone, FDA Food Grade Silicone, FDA Medical Grade Silicone, Liquid Silicone
Ethylene Propylene Diene Monomer (EPM/EPDM),
Small Silicone Bellows produced by Transfer Mold Advantages
More Precise with Minimum Flash: Rubber Transfer molded silicone membrane valve inherently have less flash (excess material that runs along the parting line of the mold) than their compression molded membrane valve because the mold remains closed when the material enters the mold cavity.
Mold with More Cavity: Rubber Transfer molding silicone rubber membrane seal require few and simple prepared material. One prepared material can fill many cavities. Compare with silicone compression molding, it is an advantage and can save a significant amount of time in the molding process, which is also an advantage over injection molding since there is not a runner to fill each cavity.
Allow Different Materials of Inserts: One of the key advantages of transfer molding over compression molding is that different inserts, such as metal parts, plastic chips, dry composite fibers, ceramics, etc., can be placed/positioned in the mold cavity before the material is injected into the cavity. This ability makes transform molding the leading manufacturing process for integrated circuit packaging and electronic components with molded terminals, pins, studs, connectors, and so on.
Short Production Cycle: Silicone Rubber Transfer Molding Membrane Gasket offers shorter cycle times than compression molding and can also provide more consistency. The process allows for tighter tolerances and more intricate parts.
Small Silicone Bellows produced by Transfer Mold Disadvantages
Material Waste: However, Rubber Transfer Molding produces more waste material than compression molding because of the sprue, the air holes and the overflow grooves that are often needed to allow air to escape and material to overflow.
Mold is more expensive than compression mold: because the design and mold is more complex, therefore tooling can also become expensive.
Production speed: It is lower than injection molding
Rubber Expansion Bellows produced by Compression Mold
Compression molding silicone bellows has the followed Advantages:
Silicone Compression molding for bellows is cost economic, and the compression molding process of bellows is quite simple when compared to injection molding.
With the development of economy, we can minimum the tolerance at 0.02-0.1mm by using good steel material, good located pins, and good mold-making equipment.
Compression molding allows for insert, fabric and encapsulating molding for prototypes with simpler handling and faster process development
Compression molding silicone bellows has the followed Disadvantages:
Due to the limitation of mold structure & compression molding way, it is hard to achieve non-flash effect by located pins & mold-making equipment.
Material Wasted due to the flash
It is hard to achieve automation unless the product structure is quite simple & production volume is large. When flash (the resin that escapes between two parts) occurs, it must be manually trimmed, thus slowing down productivity. Additionally, you’re unable to regrind this excess material, which creates more waste.
Rubber Expansion Bellows produced by LSR Injection Mold
LSR Injection Molding Silicone Bellows has the followed advantages:
1 Rubber Expansion Bellows produced by Injection Molding is High Precision, tolerance can achieve to 0.02mm, and also the flash can be minimum: because the injection molding’s material feeding system is different from compression molding, the temperature, pressure and injection way is controlled by the machine
2 Injection Molding’s production efficiency is higher than compression molding. The production time of compression molding is significantly longer than that of injection molding.
3 When the automation of the injection molding process meets short cycle times, a high-quantity production is possible. Therefore, high-quantity series can be created with injection molding, while compression molding is used rather for low and medium series of large products. For the complex product with high quantity, compression mold tool lifetime is short.
4 Liquid Silicone Material for Injection Molding is safer than solid silicone for compression molding, and the Properties of Liquid Silicone Material is good than solid silicone
Small Silicone Bellows' Major Defects:
1. Medical Silicone Bellows Flashing is too big: to solve this problem, we need to pay attention to 3 points when production; the first one is mold-design, second one is workers' skill about removing flash, and the production technology is also very important, if molding pressure is not enough, will also make the flash hard to be removed.
2. Silicone Syringe Bellows Mold misalignment & uneven wall: this problem mainly caused by mold tool, like mold-making precision, misalignment of upper mold and down mold, datum angle & the 4 located pins are not accurate enough.
3. Silicone Bellows Dust Covers Lip cracking: the situation is relative to raw materials hardness & durometer, products' structure, and die-cutting tool.
Medical Silicone Bollows produced by Compression Molding
Small Silicone Bellows Produced By Transfer Molding
Our company advantages for making Rubber Expansion Bellows:
1. Precision Own Mold-making Technology since 1998:
2. In-depth knowledge of different elastomer rubber materials molded for Silicone Bellows & Expansion Joint
3. Mature experience of flexible FDA Medical Grade Silicone Rubber Expansion joint or FDA Food Grade Silicone Bellows quality controls:
a. Silicone Rubber Bellows wall thickness sizes telorance: ± 0.05mm
b. mini or less expansion joint flashing
c. mold maintenance in aim to up and down mold plate with horizontal stripe in exact position
d. good ejected molding to improve silicone bellows production efficiency
4. Rapid prototyping with full sizes production equipment and production materials.
5. In-depth knowledge of overmolded metal + silicone rubber bellows production