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2023 guide: Forming and drying of lost foam white mold

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2023 guide: Forming and drying of lost foam white mold

The lost foam white mold is also a foam mold. Now there are many manufacturers who only make the lost foam white mold, but the production process, production technology and production method of each manufacturer are different. During production, the more important thing is the forming and drying of the lost foam white mold. These two are important matters that affect the normal use of the lost foam white mold, so we must pay more attention when making it. Today I will talk to you Let’s talk about the lost foam white mold forming and drying precautions, let’s take a look together!

Pay attention to the preheating of the mold

Note that the purpose of preheating the mold before feeding is to reduce the condensed water during bead foam molding and shorten the foam molding time. Generally, the mold preheating temperature is 50~70°C, and a reasonable choice of preheating should be made according to the season Way. At the same time, the residual water in the mold must be dried before punching to avoid surface defects. De-coring Machine

Precautions when punching

  • When using large beads (specific gravity<18g/L), a gap smaller than the radius of the pre-released beads is often left at the parting surface of the mold to facilitate the filling of the beads; use a feeding tank to feed or the specific gravity of the beads is ≥18g/L L is generally not recommended to lift the mold and feed.
  • When the feeding tank is used for feeding, it is not easy to pour too many beads into the feeding tank (generally about 2/3 of the total volume of the feeding tank).
  • When using a feeding tank to feed, the pressure of the feeding tank is generally about 0.2Mpa (sometimes it can be reasonably selected according to the structure of the mold and the thickness of the shape).
  • When using a Vento gun, attention should be paid to the amount of compressed air intake, so as not to cause the appearance of insufficient punching.

Attention to thermoforming parameter control

  • According to the thickness of different shapes and the density of beads, the molding process is reasonably selected; the molding process follows: the internal fusion is not dense, and the penetration time is prolonged: the surface is not densely fused, and the holding time is extended.
  • Under the premise of ensuring the quality of the pattern, the method of low pressure, large flow and multiple heating molding methods should be adopted as much as possible (reduce: residual volatile matter in the pattern).

Cooling attention

  • After the intake valve is closed, water cooling can only be carried out after the steam and waste heat in the mold steam chamber are exhausted; when using water cooling, pay attention to water temperature, water pressure and cooling time.
  • Under the premise of no appearance defects, the cooling time and water intake should be shortened as much as possible.

Precautions for drying white mold of lost foam

Lost foam casting white mold production line
Lost foam casting white mold production line

Area responsible

The drying operation of the formed pattern requires the relevant personnel in the white area to be responsible for the pattern drying treatment and testing, and requires the staff to be familiar with the pattern drying environment, detection methods and indicators.

Pay attention to the drying time

  • Ventilate and dry at room temperature for 2 days;
  • Ventilate and dry in a low-temperature drying room for 2 days;
  • Dry in a high temperature drying room for 1 day.

Pay attention to appearance, dryness and humidity

  • Dry at room temperature (under the ventilation condition of ambient temperature 25~35 ℃) humidity ≤ 30%;
  • Drying in the drying room (when drying in the drying room, the temperature is controlled at 25-35°C, pay attention to the ventilation conditions in the room) and the humidity is ≤25%;
  • Drying in the drying room (when drying in the drying room, the temperature is controlled at 35-40’C, pay attention to the ventilation conditions in the room) and the humidity is ≤20%;
  • Note that if the dried white mold cannot be used immediately, please put it in the transit warehouse (environmental requirements: temperature around 30C, humidity ≤ 20%), and the mold that will not be used immediately can be placed in the room temperature sunlight room.

Judgment Notes for Drying and Qualified Appearance

A good shape generally has a glossy surface and good resilience when pinched by hand. If the drying is not good, the surface will appear fish scales (the phenomenon of triple foaming that is often said to look like). In this drying process control, the residual volatile content of the pattern should be controlled below 3%, and the residual moisture in the pattern should be controlled at: <0.2% for gray iron and ductile iron parts, <0.1% for steel castings.

Other considerations

Mark the dried appearance – enter the yellow zone process, and pay attention to the safety production and fire prevention work in the area, and also pay attention to the appearance before painting and the model cluster before packing must be taken out of the drying room of.