What is SMC?
Sheet Molding Compound (SMC) is sheet form of excellent workability in capability, thermal resistance, water resistance. It contains low shrink agent, filler, hardner etc. Arrording to manufacturing processing, we put them in a mold and hot press and then harden. As It is created by quick cycles, it can be mass-produced. Further, it works in verious fields like SMC water tank, bathtub, bathroom ceiling etc.
- History
- Bayer company created Sheet Molding Compound (SMC) formed by Unsaturated Polyester Resin company and patented in 1960.
- Characteristics
- Sheet Molding Compound (SMC) is sheet form of excellent workability in capability, thermal resistance, water resistance.
SMC Molding
01Temperature
- Molded at 130 - 160℃
- Increase the surface temperature for elegant sheen
- If separation occurs, lower temperature and increase mold time
02Pressurization
time
- Pressurizing time is 30-60 seconds per 1mm
- Pressrizing time can be different depending on size, thickness, mold temperature
- Hydraulic press
- As SMC Press machine supports low pressure molding, one side is spacious and down-stroke press type.
- Need a lock
- Pressing speed *high speed : 23mm/sec *medium speed : 2mm/sec *slow speed : 0.8mm/sec
- Press capacity
- Projected Area / Developed Area
- Projected Area calculation
- Press capacity = Projected area x (50-100kg/㎠)
- Developed area calculation
- Press capacity = (Prejected area + side steep area x (1/3- 1/4) x 50 kg/㎠
- If less steep : 1/4
- If steeper : 1/3
SMC Components
01Resin
| Resin | Features |
|---|---|
| Ortho type | Wide use, Reasonable price |
| Iso type | Wide use, Water resistance, High strength |
| Bisphenol type | Erosion resistance, Heat resistance, Water resistance |
| Vinylester type | Erosion resistance |
02Low Shrink
Agent
- To keep certain level of shrinkage.
03Hardner
- Hardner makes SMC harder.
04Viscosity
material
- It increases SMC viscosity up to 600 ~ 1,000 thousand poise.
- When increased to certain level of viscosity, SMC can be manufactured evenly in press machine.
05Releasing
Agent
- Powder types of Zn-St for mixture to de-mold.
06Filler
- Filler is used for liquidity control and shrinkage decreasing etc.
07Stiffener
- 1 inch of Glass roving is used as stiffener.