Technical specifications of die casting dies

After the design of the Die-casting dies structure is completed, there are more important and more complex manufacturing, assembly, mold trial, and production application processes.

To smoothly process the dies manufacturing, trial mold, and normal use, the technical requirements for manufacturing, assembling, use, and other processes must be indicated on the assembly drawing and part drawing of the Die-casting dies.

1. Technical requirements that should be indicated in the Die-casting dies assembly drawing

 

The assembly drawing should indicate the following technical requirements

(1) The maximum external dimensions of the dies(length×width×height).

To facilitate the review of whether there is interference between the sliding components and the machine components when the dies are working, the size, position, and stroke of the hydraulic core-pulling cylinder, the size and position of the slider core-pulling mechanism, and the position of the slider to the endpoint sketches should be drawn.

(2) Choose the Die-casting machine model.

To facilitate the review of whether there is interference between the sliding components and the machine components when the dies is working, the size, position, and stroke of the hydraulic core-pulling cylinder, the size and position of the slider core-pulling mechanism and the position of the slider to the end point sketches should be drawn.

(3) Choose the inner diameter, specific pressure, or nozzle diameter of the pressure chamber.

(4) The minimum mold opening stroke (if the maximum mold opening stroke is limited, it should also be noted).

(5) Push out the itinerary.

(6) Indicate the cooling system, hydraulic system inlet, and outlet.

(7) Pouring system and main dimensions.

(8) Action stroke of special motion mechanism.

2. Technical requirements for the shape and installation position of the Die-casting dies

 

The shape and installation position of the Die-casting dies should meet the following technical requirements:

(1) The edges of each template should be chamfered 2×45°, and the mounting surface should be smooth and flat, and there should be no protruding screw heads, pins, burrs, and scratches.

(2) Mark obvious marks on the non-working surface of the dies, including the following: product code, dies number, manufacturing date, and dies manufacturer's name or code.

(3) The movable and fixed molds are respectively provided with screw holes for lifting, and the larger parts (>25kg) should also be provided with lifting screw holes. The effective thread depth of the screw hole is not less than 1.5 times the diameter of the screw hole.

(4) The relevant dimensions of the dies installation part should be by the relevant corresponding dimensions of the selected die-casting machine, and the installation and disassembly are convenient. The installation hole diameter and depth of the pressure chamber must be strictly inspected.

(5) Except for the guide sleeve hole and the oblique pinhole on the parting surface, all process holes and screw holes in the dies manufacturing process should be blocked and flush with the parting surface.

3. Technical requirements for overall assembly accuracy of Die-casting dies

 

The overall assembly accuracy of the die-casting dies should be guaranteed to meet the following technical requirements

(1) The parallelism between the dies parting surface and the installation plane of the movable and fixed dies seat plates is selected according to the provisions of the table below:

The specified unit of parallelism between the dies parting surface and the installation plane of the movable and fixed dies base (unit: mm)

The maximum linear length of the measured surface                ≤160   160~250   250~400   400~630   630~1000     1000~1600

                        Tolerance value                                                       0.06        0.08           0.1            0.12          0.16                 0.2    

(2) The verticality of the installation plane of the guidepost, guide sleeve, and fixed mold seat plate should be selected according to the provisions of the table below:

The vertical regulation of guide post and guide sleeve to the installation plane of fixed and movable dies seat plate (unit: mm)

Effective sliding length of guide post and guide sleeve          ≤40       40~63          63~100          100~160          160~250

                       Tolerance value                                                   0.015       0.02             0.025              0.030                0.040 

(3) On the parting surface, the plane of the fixed dies and the movable dies insert should be flush with the fixed mold set plate and the movable dies set plate or slightly higher, but the height should be within the range of 0.05~0.10mm.

(4) The push rod and the reset rod should be flush with the parting surface respectively. The pushrod is allowed to protrude from the profile surface, but not more than 0.1mm, and the reset rod is allowed to be lower than the profile surface, but not more than 0.05mm. The pushrod should be able to rotate flexibly in the pushrod fixed rod, but the axial clearance should not be greater than 0.10mm.

(5) All movable parts of the dies should be accurate in position, reliable in movement, and free of skew and sluggishness; no movement between relatively fixed parts is allowed.

(6) The sliding block is positioned accurately and reliably after the dies are opened. At the end of the core pulling action, the distance between the drawn core end face and the end face of the corresponding shape or hole on the casting shall not be less than 2mm. The sliding mechanism should be flexible in guiding and sliding, stable in movement, and proper clearance. After closing the dies, the sliding block and the wedge block should be compressed, the contact area is not less than 1/2, and has a certain prestress.

(7) The surface roughness Ra of the runner should not be greater than 0.4m, the connecting part should be smoothly connected, the inserting part should be close, and the molding inclination should not be less than 5°.

(8) When clamping the dies, the molding surface should fit closely. If there is a gap in some parts, the gap size should not be greater than 0.05mm (except for the exhaust groove).

(9) The cooling water channel and temperature control oil channel should be unblocked, there should be no leakage, and the inlet and outlet should be clearly marked.

(10) The surface roughness Ra of all forming surfaces is not greater than 0.4m, and all surfaces are not allowed to be damaged or rubbed. Injuries or micro cracks.

4. Dimensional tolerance and fit of structural parts of Die-casting dies

 

Die-casting dies work at high temperatures. Therefore, when selecting the matching tolerances of die-casting dies parts, not only a certain assembly accuracy is required at room temperature, but also the structural dimensions of each part are required to be stable and reliable in operation at working temperature. Especially the parts that are in direct contact with the molten metal are subjected to high pressure, high speed, and thermal alternating stress during the filling process, and the clearance with other parts is prone to change, which affects the normal progress of die casting.

The change of the fit-gap is not only related to the temperature but also related to the material, shape, volume, heating degree of the working part of the parts of the dies, and the actual fit properties after processing and assembly. Therefore, the working conditions of die-casting dies parts are very complicated. Generally, the fit clearance should meet the following two requirements:

① For the fixed parts after assembly, there will be no position deviation under the impact of the molten metal. After being heated and expanded, the deformation cannot make the fit too tight, so that the dies inserts and the sleeve plate are locally overloaded seriously, causing the dies to crack.

② For parts that are active during work, after being heated, the nature of the clearance fit should be maintained to ensure normal movement, and during the filling process, the molten metal will not cause the fit clearance.

Combined with the actual situation of die-casting dies manufacturing and use, the tolerance and matching accuracy of the main parts of the die-casting dies are now recommended as follows:

(1) Tolerance of forming dimensions: The general tolerance level is specified as IT9, H for holes, h for shafts, and GB/T180F for length. Individual special sizes can be selected IT6~T8 level when necessary.

(2) Tolerance and fit of matching parts for forming parts:

① The fixed parts of the larger parts that are in contact with the molten metal and are heated, mainly include the sleeve plate and the insert block, the insert block and the core, the sleeve plate and the sprue sleeve, the insert block and the shunt cone, etc.

The integral type and accuracy are H7/h6 or H8/h7.

The inlaid hole is H8, the largest one in the shaft is h7, and the rest of the spare parts in the shaft is js7, and the cumulative tolerance of the assembly is h7.

②The matching type and accuracy of the movable parts (including push rods, push tubes, formed push plates, sliders, slider grooves, etc.), the hole is H7, the axis is e7 Or d8.

③The height tolerance of inserts, inserts, and fixed cores is F8.

④The tolerance of the base size is taken as js8.

(3) Tolerance and coordination of template size: the tolerance of the base size is taken as js8; the core is cylindrical or symmetrical, and the centerline size tolerance of the hole from the base to the fixed core on the template is taken as js8; the core is non-cylindrical Or when it is asymmetrical, the edge dimension tolerance from the base surface to the fixed core on the template is taken as js8; the thickness dimension tolerance of the combined sleeve plate is taken as h10; the depth dimension tolerance of the insert hole of the integral sleeve plate is taken as h10.

(4) Dimension tolerance of sliding groove:

①The dimensional tolerance of the sliding block groove to the base surface is taken as f7.

②For the combined sleeve, the dimensional tolerance from the slider groove to the bottom surface of the sleeve is taken as js8.

③For the integral sleeve plate, the dimensional tolerance from the slider groove to the bottom surface of the insert hole is taken as js8.

(5) Tolerance and fit of guide post and guide sleeve: For the fixed position of the guide post and guide sleeve, the hole is H7, and the axis is m6, r6, or k6; for the clearance fit of the guide post and guide sleeve, the hole is H7, and the axis is k6 or printed. ; If the hole is H8, the axis is e7.

(6) The size between the guide post and guide sleeve and the base surface: the dimensional tolerance from the base surface to the center line of the guide post and guide sleeve is js7; the dimensional tolerance of the distance between the center line of the guide post and guide sleeve is js7, or cooperated processing.

(7) The tolerance and fit between the push plate guide post and the push rod fixed plate and the push plate: the hole is H8, and the shaft is f8 or f9.

(8) Tolerance of core table, push rod table, and corresponding dimensions: the depth of the hole table is +0.05~+0.10mm, and the height of the pillow block is -0.03~0.05mm.

(9) The tolerance level of the unmarked tolerance dimensions of various parts is IT14 level, H for holes, h for shafts, and length (height) and distance dimensions are selected according to js14 accuracy.

5.Geometric tolerances and surface roughness requirements of Die-casting dies structural parts

 

Geometric tolerance is the deviation of the surface shape and position of the part. The deviation range of the geometric tolerance of the forming part of the formed part and the reference part of all other structural parts is generally required to be within the tolerance range of the size, and no additional mark is added on the drawing. The geometric tolerances of other surfaces of the parts of the Die-casting dies are selected according to the table below and marked on the drawing.

The table below Selection accuracy grades of geometric tolerances of die casting dies parts:

Geometric tolerances of relevant elements                                                                                                       Selection accuracy

Coaxial between the axis of the fixed part of the guide post and the axis of the guide sliding part                     Level 5~6

The coaxial of each forming step surface of the circular insert to the mounting surface                                       Level 6    

Concentricity between the inner diameter of the guide sleeve and the outer diameter axis                                  Level 6~7

The axis of the fixed hole of the insert in the sleeve is coaxial with the common axis of the holes                     Level 7~8

on the other sleeves

The perpendicularity between the axis of the guide post or the guide sleeve                                                        Level 5~6

mounting hole and the parting surface of the sleeve plate

The two adjacent sides of the set of plates are the perpendicularity of the process reference plane                  Level 5~6

The perpendicularity of the two adjacent sides of the insert and the other side of the parting face                    Level 6~7

The perpendicularity between the surface of the insert hole in the sleeve and the parting surface                     Level 7~8

The perpendicularity of the axis of the core fixing hole on the insert to the parting surface                                Level 7~8

Parallelism of the two planes of the plate                                                                                                                 Level 5   

The parallelism of the opposite sides of the insert and the bottom of the parting face                                         Level 5   

The axis of the insert hole in the sleeve and the end face of the parting surface are circularly run out               Level 6~7

The radial runout of the axis of the circular insert to its end face                                                                           Level 6~7

Parallelism of the parting surface of the insert, the sealing surface of the slider, the combined surface              ≤0.05mm 

of the combined block, etc.

The surface roughness of die-casting dies parts not only affects the surface quality of the die-casting part, but also affects the use, wear, and life of the dies. It should be selected according to the work needs of the part. The appropriate surface roughness is shown in the table below.

Surface roughness of Die-casting dies:

Surface position                                                                                                                                                Surface roughness Ra/pm

The forming surface of inserts, cores and other forming parts and the surface of the gating system                      0.1~0.2

The mating surface of inserts, cores, sprue sleeves, shunt cones, and other parts                                                       ≤0.4

The mating surfaces of guide posts, guide sleeves, push rods, diagonal pins and other parts                                     ≤0.8

Mold parting surface, joint surface between each template                                                                                            ≤0.8

Support surface of core, push rod, sprue bushing, shunt cone and other parts                                                              ≤1.6

Other non-working surfaces                                                                                                                                               ≤6.3