Some knowledge about die casting mold.

1. What parts does the die-casting mold consist of?

The structure of the die can be divided into the following parts according to their functions:

(1) Molding part (movable fixed mold core, molding insert etc.)

(2) Mold base part (movable fixed mold clamping plate, AB plate, supporting plate, mold leg)

(3) Bypass system (gate sleeve, diverter cone, horizontal runner, inlet and outlet)

(4) Overflow system (overflow tank, exhaust tank)

(5) Ejection mechanism (ejector, ejector fixing plate, ejector plate, reset lever)

(6) Guide parts (guide post, guide bush, middle guide post, middle guide bush)

(7) Core-pulling mechanism (core-pulling slider, oblique guide post, detent block, spring, etc.)

(8) Others (cooling system, heating system, reinforced column, etc.)

2. What material is used for the die?

Die casting molds are mainly made of the following types of steel:

(1) H13 heat-resistant steel (for front and rear mold cores, core pulling cores, gate sleeves, shunt cones, etc.)

(2) 45 # steel (for A, B plate, slider, inclined guide post, etc.)

(3) T8, T10 (guide post, guide sleeve, thimble, reset lever, etc.)

(4) A3 steel (front and rear mold clamps, pallets, ejector plates, mold feet, etc.)

3. What is the heat treatment hardness of the die casting mold core?

The maximum hardness of the core heat treatment is: HRC45 ～ 48. The treatment is too soft (less than HRC43), the mold core is easily crushed, deformed and sticky during the production of the mold; if the treatment is too hard (higher than HRC50), the mold core is easy to crack, and some parts have hardness after nitriding Will reach HRC58-60 (such as gate sleeves, inserts, etc.).

4. What are the factors to consider for die casting molds when choosing a die casting machine?

(1) Mold installation

(2) the amount of molten metal poured

(3) clamping force

(4) Injection pressure

(5) Opening stroke

5. What is the pouring temperature and how to choose it?

The pouring temperature generally refers to the average temperature of the molten metal poured into the shot cavity and the cavity is filled. Generally, the lowest possible temperature is used while ensuring the molding and the required surface quality. The casting temperature of aluminum alloy is 650 ℃ ～ 720 ℃, the casting alloy has good fluidity, and the casting temperature can be lower; the casting temperature of thin-walled and complicated castings can be higher; If the mold is large, the heat dissipation is fast, then the casting temperature can be higher.

6. What is the mold temperature, and what is the mold temperature during normal production of aluminum alloy die-casting molds?

The mold temperature refers to the temperature of the mold during the production process. The temperature of the aluminum alloy die-casting mold during normal production is: 200 ° C to 280 ° C. Generally, for castings with thinner wall and more complicated structure, the mold temperature should be higher.

7. What is the filling time? How to choose the filling time?

The time required for the molten metal to start to fill the cavity is called the filling time. The filling time of aluminum alloy die casting is generally 0.01S ~ 0.1S.

The selection principle of the filling time is:

(1) If the alloy pouring temperature is high, the filling time should be longer;

(2) If the mold temperature is high, the filling time is longer;

(3) If the thick wall is far from the gate, the filling time should be longer;

(4) For alloys with high heat of fusion, the filling time should be longer;

(5) When the exhaust effect is poor, the filling time should be longer.

8. What is holding time? What is the role of holding pressure? How to choose holding time?

The holding time is also called the holding time. It is the time required for the solidification under the action of the specific pressure of the pressure after the metal liquid fills the cavity. The purpose of holding pressure is to crystallize the solidifying metal under pressure, thereby obtaining a casting with dense internal structure. The holding time of die-casting aluminum is 1 to 2 seconds when the wall thickness of the casting is less than 2.5MM, and 3 to 8 seconds when the wall thickness of the casting is 2.5 to 6MM.

The selection principles are:

(1) The crystallization temperature range of the die-casting alloy is higher, and the holding time is longer;

(2) The wall thickness of the casting is large, and the holding time can be longer;

(3) If it is a top gate, the holding pressure time can be longer, and the thick gate holding time should be longer.

9. What is retention time? How to choose the retention time?

Retention time is also called cold mold time, which is the residence time of the casting in the die. That is, the time required from the start of holding pressure to the time when the casting is ejected from the mold. Sufficient retention time ensures that the casting is fully solidified in the model, cooled and has a certain strength. Usually the shortest time to make the castings not deformed and cracked is appropriate. Die casting aluminum alloy castings have a retention time of 5S ~ 30S, which has a direct relationship with the wall thickness of the casting. The thicker the casting wall thickness, the longer the retention time.