For our most complex jobs, our air set operation utilizes chemically bonded sand to ensure tight dimensional tolerances and casting integrity. Typical airset moldings range from under one ounce up to 300 pounds.
Chemically Bonded Air Set Production Scale
- High Complexity Castings
- Castings up to 300 pounds
- Mold Size up to 65” x 42” and 24” over 24”
- Single Pull Through System
- 50 molds per shift
The airset molding method is also referred to as no bake molding, making AFW a no bake foundry. The use of Silica sand, which is chemically bonded with resins or binders, versus naturally bonded sand lends certain casting benefits. Air set production affords better tolerances/dimensional capabilities, better surface finish and the ability to fill in deep or wide molds.
With this process there are no specific run sizes. We can do 1 to 10,000 pieces. Any type of casting can be molded with a wide choice of alloys.
- Simplified sand mix, good flowability of the sand mix
- Uniform hardness throughout the mold
- Exact dimensional control
When the box is full Operator #1 sends the mold to the rollover/draw machine. The mold will cure in this position for a preset amount of time before it is automatically clamped and rolled over. The molds that are released from the box are sent to the assembly station and once complete move to the the closing station while the mold boxes are sent back to the filling station.
Optimization began with putting in a Palmer 2000# Mixer which increased the sand fill rate of the boxes to 1500#s per minute.
The heart of the mixer is the RFID system which essentially allows “teaching” the mixer how to fill each mold box. A program is utilized to control how much sand is delivered to the mold box and as well as where in the box the sand is placed—steps that are accomplished with dual axis control and a powered conveyor. This puts into motion a repeatable process which not only eliminates wasted operator time but also wasted sand as well.
Operator #2 continues the process by setting the necessary cores and closing the molds.
Once the mold has been closed it is transferred into the pouring station only a few feet away where the operator pours the mold.
All of Operator #2’s operations are performed within the cycle time of Operator #1—providing us a very high rate of efficiency.
As additional molds are made, the poured molds index down an automatic conveyor until they reach the dump station. There, the Knockout/Saw Operator uses a lift table to lift the mold off the conveyor line and dump it into the shakeout deck where the mold is broken apart and the casting is removed with an overhead crane.
Once the casting is knocked out it is allowed to cool and the gating is removed at the band saw operation. From there the casting is sent to grinding where the parting lines and riser contacts are removed.
Finally, the casting is sent down a conveyor to the blast machine where the part is blasted and ready for inspection.
Takeaways from the optimization of the air set mold making line include:
- A better understanding of one piece work flow which has increased our operational efficiency
- Establishment of a pull system has improved productivity.
- A reduction of material handling and tooling – has increased efficencies.
- The addition of overhead cranes has reduced physical labor.