What are the common causes of damage to injection molds?

1, Design flaw: congenital deficiency leading to shortened lifespan
Insufficient structural strength
Bending of the moving template is a typical design flaw. The mold for the frame of a certain mobile phone was permanently deformed under injection pressure due to the use of A3 high-strength steel plate, resulting in product size deviation. The solution is to use high-strength mold steels such as H13 and S136, and add support columns below the moving template to increase the thickness of the template by 20% -30%.
Guidance system failure
The damage to the guide column is often caused by excessive lateral displacement force. For example, a large TV casing mold generated a lateral force of 3 tons during injection due to uneven wall thickness of the plastic parts, causing the surface of the guide column to become rough. Preventive measures include: adding cylindrical positioning keys on the parting surface to ensure that the perpendicularity between the guide column hole and the parting surface is ≤ 0.01mm; the heat treatment hardness of the guide column needs to reach HRC52-56.
Defects in exhaust system
The mold for a smartwatch case experienced a significant increase in cavity pressure to 120MPa during melt filling due to the exhaust groove depth being only 0.01mm, leading to mold cracking. The optimization plan adopts a segmented exhaust design: a main exhaust groove with a depth of 0.03-0.05mm is set on the parting surface, and an auxiliary exhaust hole with a depth of 0.005-0.01mm is added at the end of the core.
2, Material issue: Heat treatment process determines mold life
Improper material selection
A certain bone conduction earphone mold was made of NAK80 pre hardened steel, but collapsed after continuous production of 30000 molds. The fundamental reason is that this material is only suitable for thin-walled parts, and the product has a wall thickness of 3mm. After using DC53 cold work mold steel, the service life has been increased to 150000 molds.
Defects in heat treatment process
Due to a temperature deviation of ± 10 ℃ during vacuum quenching, the surface hardness of a certain AR eyeglass frame mold was uneven, resulting in localized soft spots. By using laser quenching technology, the hardness uniformity is improved to ± 1HRC, and the mold life is extended by three times.
Surface treatment failure
A folding screen mobile phone hinge mold was treated with TD (molten salt carburizing), but due to insufficient processing time, the thickness of the carburizing layer was only 0.02mm, and wear occurred after 5000 production cycles. After optimization, the thickness of the infiltration layer reaches 0.05mm, and the wear resistance is improved by 5 times.
3, Operational error: Sudden malfunction caused by human factors
Lack of mold installation specifications
During the installation of a drone shell mold, the ejector pin was bent and broken due to the ejector pin not retracting and directly closing the mold. Standard operating procedure requirement: Before installing the mold, red lead powder should be used to check the displacement of the ejector pin; Before closing the mold, it is necessary to manually rotate the screw to confirm that there is no interference.
Parameter setting error
A certain medical injector mold cracked due to the injection pressure set at 180MPa (far exceeding the design value of 120MPa). By introducing an intelligent parameter monitoring system, the machine will automatically shut down when the pressure exceeds the threshold, avoiding accidents.
Negligence in maintenance and upkeep
Due to the failure to regularly clean the exhaust groove of a certain car dashboard mold, the melted material was burnt and blocked, causing local overheating and deformation of the mold. Establish a graded maintenance system: clean the exhaust groove every shift, check the top pin lubrication every week, and polish the mold cavity every month.
4, Improper maintenance: Accumulation of chronic damage leading to sudden failure
Cooling system malfunction
The cooling efficiency of a server chassis mold decreased by 40% due to the accumulation of 0.5mm scale on the inner wall of the waterway. The mold temperature increased from 80 ℃ to 120 ℃, causing thermal deformation of the template. Using a pulse type scale cleaning machine, cleaning once every quarter can keep the waterway unobstructed.
Wear and tear of the ejection mechanism
A certain laptop shell mold experienced severe material leakage due to the expansion of the gap between the top rod and the hole from 0.05mm to 0.15mm. By adopting self-lubricating coating technology, the friction coefficient was reduced from 0.2 to 0.05, and the gap expansion speed was slowed down by 80%.
The slider mechanism is stuck
A certain smart speaker mold tilted during core pulling due to insufficient length of the slider guide groove (only one-third of the total length of the slider), resulting in wear of the guide groove. The improvement plan is to extend the length of the guide groove to 2/3 of the total length of the slider and add a limit block.
5, Preventive solution: Building a full lifecycle management system
Digital Mold Design
Apply Moldflow simulation software for flow analysis, predict pressure distribution and temperature field changes during the melt filling process, and identify potential risk points in advance. A certain mobile phone manufacturer reduced the number of mold trials from 5 to 2 through simulation optimization, shortening the development cycle by 40%.
Intelligent monitoring system
Deploy IoT sensors to monitor real-time parameters such as mold temperature, pressure, and vibration. A certain household appliance enterprise achieved a fault warning accuracy rate of 92% and a 65% reduction in unplanned downtime by installing 128 monitoring points.
Standardized maintenance process
Develop the "Injection Mold Maintenance SOP" to clarify:
Daily: Check the lubrication of the top pin and clean the exhaust groove
Weekly: Measure key dimensions of the mold and check the sealing of the waterway
Monthly: Polishing the mold cavity and replacing vulnerable parts
Personnel skill training
Establish a three-dimensional training system of "theory+practice+case", focusing on strengthening:
Cognition of Mold Structure Principles
Rapid diagnosis of abnormal phenomena
Emergency response process drill