How to evaluate the cost and cycle of LPDC mold modification and cavity modification?
Product iteration and drawing changes will lead to cavity modifications, which are high-frequency requirements throughout the entire lifecycle of LPDC molds.
1、 Proportion of labor hours and costs corresponding to different types of modifications
Partial welding and polishing of the cavity is a minor modification with a single modification area. The cost is generally 8% -15% of the newly opened mold, and the cycle is 3-7 days. It is suitable for local fillet and wall thickness adjustment.
The modifications to the slider and core pulling structure belong to the category of moderate modifications, involving mating surfaces and motion mechanisms, with costs accounting for 25% -40% of the new mold opening, and a cycle time of 10-18 days.
The modification of the cooling channel and main gate is a major process change that requires re simulation verification, with a cost accounting for 45% -60% of the new mold opening and a cycle time of 20-30 days.
The overall cavity is re milled, removing the original cavity and redoing it. The cost is close to 70% of the cost of opening a new mold, and the cost-effectiveness is low. Most customers will directly open a new mold.
After receiving the drawing changes, Xinfeng Machinery first evaluates the modification boundaries, outputs the modification plan and risk statement.
2、 Process limitations of weld repair
H13 mold surfacing must use the same type of hot work steel welding material, and after welding, stress relief and tempering must be carried out. Otherwise, residual stress in the welding area will cause cracks after 1000-2000 mold cycles of production.
The thickness of a single welding layer should not exceed 3mm, and multi-layer welding requires layered tempering to prevent excessive brittleness and thermal shock cracking in the welding area.
After nitriding, the cavity welding layer is completely destroyed, and after the modification is completed, it needs to be re nitrided to restore the surface wear resistance.
3、 Differences in overseas customers' demands for payment changes
Southeast Asian customers have fast product iteration and limited budgets. They prioritize welding and redesign, and try to avoid new mold openings. 78% of change orders are prioritized for evaluation and mold repair.
North American automotive customers have strict control over drawing changes, and after the modification, they must undergo a new first article inspection and PPAP update, which is cumbersome and time-consuming.
European customers will evaluate the remaining life of the modified mold, and if the remaining mold cycles are less than 5000, they are more inclined to directly open a new mold.
The shaping cycle of construction machinery products in the Middle East is long, the frequency of modification is low, and the magnitude of single modification is large. Many directly choose new molds.
4、 Hidden risks brought by the facelift
The metallographic structure of the locally welded area is inconsistent with the base material, resulting in a decrease in thermal fatigue performance, and the welding area is more prone to thermal cracking, with a lower lifespan than the original cavity.
After the modification, the relative positions of the cooling channel and exhaust groove have changed, and the original solidification and filling balance has been disrupted. It is highly likely that a new mold test and process adjustment will be required.
Repeated welding has accumulated fatigue in the base metal and significantly reduced the overall life of the mold. It is not recommended to weld more than 3 times in a single area.
5、 Long tail traffic layout ideas
Revision, mold repair, and mold refurbishment belong to the category of after-sales operation and maintenance search, targeting foundry procurement and maintenance engineers.
Keywords: LPDC mold modification cost, low pressure casting die cavity rework;
Problem class: Can we weld repair LPDC H13 mold;
Comparison class: modify existing LPDC mold vs make new mold.
Suitable for the mold maintenance service page, to handle the traffic of existing mold customers.
6、 Common misconceptions in the industry
Misconception 1: Welding modifications can be made infinitely, and repeated welding can cause fatigue of the substrate. After multiple welding, the mold will be directly scrapped.
Misconception 2: Changing the mold only requires modifying the cavity, and there is no need to review the cooling, exhaust, and sprue. Changing the cavity will break the original filling and solidification balance.
Misconception 3: Directly mass produce after modifying the mold cavity, without the need for mold testing. If the size and filling state change, a new mold must be tested and verified.
FAQ
Q: What is the proportion of small-scale welding modification cost to new mold opening cost?
A: Generally 8% -15%, with a cycle of 3-7 days, suitable for fine adjustment of rounded wall thickness.
Q: What treatments are required after H13 welding?
A: Stress relief tempering after welding, and re nitriding after the modification is completed.
Q: How does the lifespan of the welding zone mold compare to the base material?
A: The thermal fatigue performance is relatively weak, making it more prone to thermal cracking.
Q: How many times is it recommended to weld in a single area?
A: Try to control within 3 cycles to avoid the accumulation of matrix fatigue.
Q: When do European customers suggest opening a new mold?
A: If the remaining stable module count after the facelift is less than 5000, priority will be given to opening a new one.
Q: How long is the typical cycle for slider redesign?
A: 10-18 days, involving sports coordination and greater debugging workload.
Q: Do I need to re nitride after nitriding cavity welding?
A: The nitride layer in the welding area has failed, and it must be re nitrided after the modification is completed.
Q: Do I need to test the mold again after the redesign?
A: Changes in cavity structure and filling and solidification conditions require retesting of the mold.
