Analysis of the Casting Process and Mold Design for ZL103 Alloy Bracket

Figure 1 depicts the structural diagram of the bracket part, which is made of ZL103 alloy. The complexity of the part's shape, the presence of numerous holes, and its thin thickness make it difficult to eject during the casting process and may lead to deformation and dimensional tolerance issues. Given the high dimensional accuracy and surface quality requirements, it is crucial to carefully consider the feeding method, feeding position, and part positioning in the mold design.

The die-casting mold structure, as shown in Figure 2, follows a three-plate type design with a two-part parting line. The center feeds from the point gate, providing a satisfactory effect and an aesthetically pleasing appearance.

The initial gate form chosen for the die-casting mold was a direct gate. However, it was observed that the connection area between the residual material and the casting was relatively large after part formation, making it challenging to remove the residual material. The presence of residual material negatively impacted the quality of the upper surface of the casting, causing shrinkage cavities that did not meet the casting requirements. To address this, a point gate was adopted and proved to be effective in producing castings with smooth surfaces and uniform internal structures. The inner gate diameter was determined as 2mm, and a transition fit H7/m6 was utilized between the gate bushing 21 and the fixed mold seat plate 22. The inner surface of the gate bushing was smoothed to facilitate the separation of condensate from the main channel, achieving a surface roughness of Ra=0.8µm.

Considering the limitations posed by the shape of the gating system, a two-parting surface approach was employed in the mold to address part separation from the sprue sleeve and the casting surface. Parting surface I was used to separate the remaining material from the sprue sleeve, while parting surface II broke the remaining material from the casting surface. The baffle plate 24, located at the end of the tie rod 23, facilitated the sequential separation of the two parting surfaces. Furthermore, the tie rod 23 acted as a distance fixer. The length of the mouth sleeve was optimized to ease the removal of the remaining material.

After parting, the guide post emerges from the guide hole of the movable template 29. Consequently, during mold closure, the mold cavity insert 26 is accurately positioned by the nylon plunger 27 on the movable template 29.

The initial mold design incorporated a one-time push-out using a push rod. However, this led to problems such as deformation and size out-of-tolerance in the castings. Extensive research and experimentation revealed that the thin thickness and larger length of the castings resulted in an increased tightening force on the center insert of the moving mold, leading to deformation when subjected to pushing forces on both ends. To resolve this issue, a secondary pushing mechanism was implemented. This mechanism used a hinge connection structure, in which the upper push plate 8 and lower push plate 12 were connected through two hinge plates 9 and 10 and a pin shaft 14. The pushing force from the die-casting machine's push rod was initially transmitted to the upper push plate 8, enabling simultaneous movement for the first push. Once the limit stroke of the limit block 15 was exceeded, the hinge bent, and the pushing force from the die-casting machine's push rod acted solely on the lower push plate 12. At this point, the upper push plate 8 stopped moving, allowing for the second push.

The mold's working process involves the rapid injection of the liquid alloy under pressure from the die-casting machine, followed by mold opening after forming. During mold opening, the I-I parting surface is initially separated, allowing for the separation of the remaining material at the gate from the sprue sleeve 21. Subsequently, as the mold continues to open, tension rods 23 affect the separation of the parting surface II, pulling off the remaining material from the ingate. The entire piece of remaining material can be removed from the center insert of the fixed mold. The ejection mechanism is then initiated, commencing the first push. The lower hinge plate 10, pin shaft 14, and upper hinge plate 9 enable the push rod of the die-casting machine to push both the lower push plate 12 and the upper push plate 8 simultaneously, smoothly pushing the casting away from the moving plate and inserting it into the mold center's insert 3 while activating core-pulling of the fixed insert 5. As the pin shaft 14 moves away from the limit block 15, it bends toward the center of the mold, resulting in the loss of force by the upper push plate 8. Consequently, the bolt push rod 18 and push plate 2 stop moving, while the lower push plate 12 continues moving forward, pushing the push tube 6 and push rod 16 to propel the product out of the cavity of the push plate 2, achieving complete demoulding. The ejection mechanism is reset to its initial position during mold closure, completing one working cycle.

During mold usage, the surface of the casting exhibited a mesh burr that expanded as the number of die-casting cycles increased. Research unveiled two causes for this issue: large mold temperature differences and significant cavity surface roughness. To mitigate these problems, preheating the mold prior to usage and implementing cooling during production are essential. The mold is preheated to a temperature of 180°C, and the mold cavity's surface roughness is controlled, maintaining it at Ra≤0.4µm. These measures significantly enhance the quality of the castings.

The mold's surface undergoes nitriding treatment to improve wear resistance, and proper preheating and cooling are ensured during usage. Additionally, stress tempering is performed after every 10,000 die-casting cycles, and the cavity surface is polished and nitrided. These steps significantly extend the mold's lifespan. Currently, the mold has exceeded 50,000 die-casting cycles, demonstrating its reliability and durability.

In conclusion, the analysis of the casting process and mold design for the ZL103 alloy bracket highlights the importance of considering factors such as feeding method, feeding position, and part positioning to achieve high dimensional accuracy and surface quality. The chosen gate form, point gate, proved effective in producing castings with smooth surfaces and uniform structures. The two-parting surface mechanism, alongside the hinge-based secondary push-out design, resolved issues related to deformation and size out-of-tolerance in the castings. Following proper mold preheating, controlled mold cavity surface roughness, and preventive measures such as nitriding, stress tempering, and polishing, a mold with an extended lifespan and improved casting quality was achieved. The success of this project illustrates Tallsen's commitment to quality and innovation.

Expanding on the topic of "How to take out the push-pull drawer"...

Drawers are an essential piece of furniture in our homes, and it's important to not only clean the surface but also maintain the inside to keep it in good condition. Cleaning the drawers regularly is essential for the longevity of the furniture and the items stored inside.

To remove and reinstall the drawers, start by emptying out all the contents of the drawer. Once the drawer is empty, pull it out to its full extent. On the side of the drawer, you will find a small wrench or lever. These mechanisms may differ slightly depending on the drawer, but the basic principle remains the same.

To remove the drawer, locate the wrench and remove it by either pushing upwards or downwards. Use both hands to gently pull out the wrench from the top and bottom simultaneously. Once the wrench is detached, the drawer can be easily taken out.

To reinstall the drawer, simply align the drawer with the slide rails and push it back into place. Make sure it slides in smoothly without any resistance. Once in place, give it a gentle push to ensure it is securely installed.

Regular maintenance of the drawers is crucial to keep them in good condition. Start by cleaning the drawer regularly. Use a damp cloth to wipe down the surface and remove any debris or dust. Be careful not to leave any moisture behind as it can lead to corrosion of the drawer and damage the items stored inside. After wiping the drawer, dry it thoroughly with a dry cloth before placing the items back inside.

It is also important to avoid exposing the drawer to corrosive gases or liquids. This is especially true if the drawer is made of iron, wood, or plastic. Contact with corrosive substances can lead to damage and rot. Be cautious and avoid placing corrosive objects near the drawers to prevent any damage.

Now let's discuss the process of removing the drawer slides. There are different types of slide rails, such as three-section tracks or sheet metal slide rails. To remove the drawer slides, follow these steps:

1. First, determine the type of slide rail used in your drawer. In the case of a three-section track, gently pull out the cabinet. Be cautious and check for any sharp objects protruding from the sides of the cabinet, commonly known as plastic bullet cards. Press down on the plastic bullet cards to release the cabinet. You will hear a distinct sound indicating that it has been unlocked. Once unlocked, the cabinet can be easily taken out. Make sure to keep the cabinet level and avoid using excessive force to prevent damage to the tracks on both sides. Adjust the position of the cabinet as needed before reinstalling it.

2. If you have sheet metal slide rails, start by pulling out the cabinet carefully while keeping it stable. Look for any pointed buttons and try pressing them down with your hands. If you feel a click, it means the button has been released. Gently take out the cabinet, keeping it flat to avoid causing damage to the track. Check the drawer's track slide for any deformations or issues. If there are any deformations, adjust the position and fix them before reinstalling the drawer using the original method.

In conclusion, maintaining the cleanliness and functionality of drawers is crucial for the overall maintenance of furniture. By regularly cleaning the drawers and being cautious about potential damage from corrosive substances, we can prolong the lifespan of our furniture and keep our homes organized.

An Analysis of the Casting Process

The bracket part, made of ZL103 alloy, has a complex shape with numerous holes and thin thickness. This poses challenges during the ejection process, as it is difficult to push out without causing deformation or dimensional tolerance issues. The part requires high dimensional accuracy and surface quality, making the feeding method, feeding position, and part positioning crucial considerations in mold design.

The die-casting mold, depicted in Figure 2, adopts a three-plate type, two-part parting structure, with a center feed from the point gate. This design yields excellent results and an appealing appearance.

Initially, a direct gate was used in the die-casting mold. However, this resulted in difficulties during the removal of residual materials, affecting the quality of the casting's upper surface. Moreover, shrinkage cavities were observed at the gate, which did not meet the casting requirements. After careful consideration, a point gate was chosen as it proved to produce smooth casting surfaces with uniform and dense internal structures. The inner gate diameter was set at 2mm, and a transition fit of H7/m6 was adopted between the gate bushing and the fixed mold seat plate. The gate bushing's inner surface was made as smooth as possible to ensure proper separation of the condensate from the main channel, with a surface roughness of Ra=0.8μm.

The mold employs two parting surfaces due to the gating system's shape limitations. Parting Surface I is used to separate the remaining material from the sprue sleeve, while Parting Surface II is responsible for removing residual material from the casting surface. The baffle plate at the end of the tie rod facilitates sequential separation of the two parting surfaces, while the tie rod maintains the desired distance. The length of the mouth sleeve (remaining material separated from the sprue sleeve) is adjusted to aid in the removal process.

During parting, the guide post emerges from the movable template's guide hole, allowing the mold cavity insert to be positioned by the nylon plunger installed on the movable template.

The original design of the mold included a one-time push rod for ejection. However, it resulted in deformations and size deviations in the thin, long castings due to the increased tightening force on the moving mold's center insert. To address this issue, secondary pushing was introduced. The mold incorporates a hinge connection structure, allowing simultaneous movement of the upper and lower push plates during the first push. When the movement exceeds the limit stroke, the hinge bends, and the push rod's force only acts on the lower push plate, stopping the motion of the upper push plate for the second push.

The mold's working process involves the rapid injection of liquid alloy under pressure, followed by the mold opening after formation. The initial separation occurs at the I-I parting surface, where the remaining material at the gate is detached from the sprue sleeve. The mold continues to open, and the remaining material from the ingate is pulled off. The ejection mechanism then initiates the first push, wherein the lower and upper push plates move forward synchronously. The casting is smoothly pushed away from the moving plate and the fixed mold's center insert, allowing for core-pulling of the fixed insert. As the pin shaft moves away from the limit block, it bends towards the mold's center, causing the upper push plate to lose force. Subsequently, only the lower push plate continues to move forward, pushing the product out of the cavity of the push plate through the push tube and push rod, completing the demolding process. The ejection mechanism resets during mold closure through the action of the reset lever.

During mold usage, the casting surface initially exhibited a mesh burr, which gradually expanded with each die-casting cycle. Research identified two factors contributing to this issue: large mold temperature differences and a rough cavity surface. To address these concerns, the mold was preheated to 180°C before use and maintained a surface roughness (Ra) of 0.4μm. These measures significantly improved casting quality.

Thanks to the nitriding treatment and proper preheating and cooling practices, the mold's cavity surface enjoys enhanced wear resistance. Stress tempering is carried out every 10,000 die-casting cycles, while regular polishing and nitriding further increase the mold's lifespan. To date, the mold has successfully completed over 50,000 die-casting cycles, demonstrating its robust performance and reliability.