On-site Troubleshooting of Uneven Lubrication & Nozzle Blockage on Double-Side Oil Feeder Matched to 160T Servo Punch

On-site Troubleshooting of Uneven Lubrication & Nozzle Blockage on Double-Side Oil Feeder Matched to 160T Servo Punch Press, Stabilizing Stamping Surface Quality and Reducing Die Abrasion

Lubrication is a fundamental auxiliary process in precision metal stamping. The double-side oil feeder is widely installed on servo punch press production lines to deliver stamping oil evenly on both upper and lower surfaces of metal strips before entering the die cavity. Proper oil film can reduce friction between raw material and die cutting edge, restrain heat accumulation during high-speed stamping, lower burr generation, extend die service life, and improve surface finish of finished stamped components. For automotive structural parts, battery conductive sheets and precision terminal products, oil film uniformity directly determines whether the surface scratches, material galling, dimensional fluctuation and die chipping defects can be controlled within acceptable limits. Once the oil feeder suffers nozzle blockage, unstable oil supply pressure, inconsistent oil output on left and right sides or dripping failure, the whole production line will face continuous quality risks.

Recently, our after-sales service department received an urgent service ticket from an automotive metal component manufacturer in the Yangtze River Delta. The customer’s production cell adopts a 160T servo punch press paired with a NC servo feeder and automatic double-side oil feeder, continuously stamping cold-rolled steel structural brackets with a material thickness of 1.2 mm. After running normally for 14 months, the workshop quality inspector reported a rising proportion of parts with surface galling, uneven dark oil stains and local burr overrun. The operators checked the oil feeder roughly and found that several oil spray nozzles produced weak oil mist while some outlets stopped spraying completely; residual stamping oil dripped intermittently on the feeding guide plate, contaminating the strip surface and causing secondary stamping defects. Within one 8-hour shift, the non-conforming rate climbed to 4.7%. The customer tried to clean individual nozzles manually, but the fault recurred after 1 to 2 hours of production. Frequent quality sorting, rework and die polishing brought heavy labor burden, and the customer worried that long-term insufficient lubrication would cause irreversible wear on the expensive carbide die set, so they contacted our after-sales hotline for professional support immediately.

Upon receiving the customer’s fault report, our service center triggered the priority after-sales emergency response workflow for stamping auxiliary equipment. The whole service chain adopted standardized procedures, with clear division of labor among remote support team, spare parts warehouse, field engineer and after-sales follow-up group. The specific service measures carried out are as follows:

1. 24/7 remote technical hotline for preliminary fault classification and data collection Within 15 minutes after the ticket was submitted, a dedicated automation after-sales engineer established a voice and video connection with the customer’s on-site maintenance supervisor. The engineer guided the customer to record real-time parameters on the oil feeder HMI, including main oil pump outlet pressure, left side oil flow rate, right side oil flow rate, air supply pressure for atomization, oil tank liquid level and running time. Meanwhile, the engineer required the customer to shoot short videos of nozzle spraying status, oil return pipeline and filter appearance. According to the feedback, the remote team excluded the failure of the main pump power unit at the first stage, and preliminarily judged the composite fault as nozzle blockage mixed with filter element clogging, pipeline sediment accumulation and pressure regulating valve parameter drift. The remote engineer issued a pre-inspection guide sheet, telling the customer not to disassemble the precision flow regulating valve blindly to avoid secondary damage to internal sealing components. The work order was formally locked in the after-sales management system.
2. Regional spare parts warehouse priority reservation and preparation of matching accessories Our East China regional spare parts warehouse keeps standardized inventory for double-side oil feeder series. After remote preliminary diagnosis, the warehouse team reserved atomizing nozzles, stainless steel filter elements, pressure gauge assemblies, oil-resistant sealing O-rings and cleaning agent kits within 60 minutes. The warehouse staff checked the accessory model consistency one by one against the serial number of the customer’s oil feeder, avoiding the risk of model mismatch. All spare parts and special cleaning tools were packed into the service toolbox, ready for the on-site engineer to pick up directly, which greatly shortened the waiting time caused by separate procurement of small accessories.
3. Dispatch of certified auxiliary equipment service engineer for on-site arrival According to the regional service coverage map, our certified engineer who is proficient in stamping lubrication system maintenance departed to the customer factory. Before entering the workshop, the engineer strictly implemented lockout-tagout safety rules: cut off the air source of the oil feeder, shut down the 160T servo punch press and servo feeder, lock the main power switch and hang maintenance warning signs. Only after confirming that there was no residual pressure in the oil circuit and air circuit did the engineer start the step-by-step inspection work, to prevent accidental oil injection, equipment jog or personal injury during disassembly.
4. On-site technical training and handover of preventive maintenance documents After the fault was eliminated and the equipment was verified to run stably, the engineer did not finish the service simply. He gathered the workshop operators and maintenance technicians, carried out face-to-face training covering oil feeder daily inspection, oil selection specification, filter replacement cycle, nozzle cleaning method, abnormal parameter judgment and simple emergency handling. A customized lubrication system maintenance checklist was printed and handed over on site, and the equipment was added to our regular quarterly proactive inspection plan.
5. Multi-node post-service follow-up mechanism The after-sales follow-up clerk set scheduled follow-up calls at 24 hours, 72 hours and 7 days after the on-site service was completed. The follow-up content focused on whether the oil feeder maintained stable atomization effect, whether the product qualification rate recovered, whether new dripping or blockage appeared, and whether the on-site personnel had questions about maintenance operation. If any new abnormality is fed back, the service team will respond again in time without additional service charge within the warranty scope.

The engineer adopted the isolation diagnosis method, separating air circuit, oil circuit, filter assembly, nozzle group and control module one by one to locate the root causes step by step.

Step one: Visual inspection and parameter reading. The engineer first called up the historical operation log of the oil feeder on the touch screen. The design rated flow for each side was 12 ml/min, but the actual flow of the left oil circuit fluctuated between 2–6 ml/min, and the right oil circuit was unstable at 7–10 ml/min. The atomization air pressure displayed 0.32 MPa, while the recommended standard range was 0.20–0.25 MPa. The pressure was set higher to compensate for insufficient oil output, which aggravated oil splashing and dripping at individual outlets. When observing the nozzle group, it was found that the inner orifice of 4 out of 12 nozzles was covered with dark brown sticky sediment, formed by the oxidation of stamping oil mixed with fine iron powder, dust and emulsified impurities. These sediments narrowed the flow channel and even blocked the oil passage partially.

Step two: Dismantle and inspect primary and secondary filter elements. The engineer shut down the oil pump, drained a small amount of oil in the pipeline, and removed the suction filter inside the oil tank and the fine filter before the nozzle manifold. The filter screen was blocked by a large amount of iron powder and oil sludge. The filter clogging caused insufficient oil supply to the manifold, leading to low and unstable outlet flow. The customer had never replaced the fine filter element since the equipment was put into use, only cleaned the oil tank surface occasionally.

Step three: Check oil supply pipeline and pressure regulating valve. The engineer inspected the oil hose and manifold. Some hoses were bent for a long time and had inner wall deformation; a small amount of oil sludge deposited at the bottom of the horizontal manifold. The oil pressure regulating valve had been adjusted many times by operators without professional guidance, and the internal spring fatigue caused pressure drift. Even if the knob was fixed, the oil supply pressure fluctuated with the change of oil temperature. When the oil temperature rose after long-time running, the viscosity of stamping oil decreased, and dripping became serious. When the oil temperature was low at the start of shift, the oil flow was obviously insufficient.

Step four: Verify compressed air quality. The engineer connected a test instrument to the air inlet of the oil feeder. The compressed air contained tiny water vapor and oil pollution from the factory air compressor. Moisture mixed into the stamping oil would accelerate oil deterioration, promote sludge formation, and indirectly accelerate repeated nozzle blockage. The customer’s air pipeline was not equipped with a terminal drying filter for the lubrication equipment.

Step five: Confirm oil type and replacement cycle. The customer mixed two different brands of stamping oil by mistake in the last oil replenishment. Different base oils and additives had incompatibility reactions, forming sticky colloidal precipitates. This precipitate was the main component of the sludge blocking filters and nozzles.

After the layered inspection, the engineer confirmed that this was a multi-factor composite fault, not a single nozzle blockage. The core factors included mixed oil liquid deterioration, long-term unreplace clogged filters, pipeline sludge accumulation, pressure valve parameter misadjustment and unpurified compressed air.

The repair scheme targeted all identified root causes instead of only cleaning the blocked nozzles temporarily.

1. Full oil circuit cleaning and oil liquid replacement. The engineer drained all deteriorated mixed oil in the oil tank, cleaned the tank inner wall with professional cleaning agent, wiped away oil sludge and sediment completely. After the tank was dried, new stamping oil of the model specified in the equipment manual was refilled to the standard liquid level. The engineer emphasized that mixing different brands and types of lubricating oil was forbidden.
2. Replace all failed filter components. The suction filter in the oil tank and the fine filter before the manifold were replaced with new stainless steel filter elements. The old filters were kept for the customer as samples, so the maintenance team could intuitively understand the accumulation degree of impurities.
3. Disassemble, clean and calibrate all nozzle assemblies. All 12 atomizing nozzles were disassembled one by one, soaked in special cleaning solvent, cleaned with ultrasonic cleaning tool to remove the sticky sediment inside the orifice. After cleaning, the nozzles were reassembled, and the spray angle and atomization effect were tested one by one to ensure uniform mist output without large oil drops. Damaged sealing rings at nozzle joints were replaced to eliminate dripping.
4. Rearrange oil pipelines and recalibrate pressure parameters. The deformed oil hoses were replaced, the pipeline layout was adjusted to avoid sharp bending and dead corners that easily deposit sludge. The oil pressure regulating valve and atomization air pressure valve were reset to the factory recommended values. The engineer locked the valve position after calibration and marked it on the valve body to prevent random adjustment by operators.
5. Add terminal air drying filter. A small air-water separator and precision filter were installed at the air inlet of the oil feeder to remove water and oil impurities in compressed air, slow down the oxidation and deterioration speed of stamping oil.

After all the rectification items were completed, the engineer started the oil feeder and matched 160T servo punch press for continuous test operation. The equipment ran at the customer’s normal production stroke rate of 45 strokes per minute for a continuous 4-hour verification test. During the whole verification period, all nozzles produced uniform and fine oil mist on both sides of the steel strip. The flow data on HMI remained stable near the rated value, no dripping, no intermittent oil breakage occurred. The stamped bracket samples were randomly sampled and inspected, surface galling and oil stain defects disappeared, burr height was controlled below 0.02 mm, and the product non-conforming rate dropped back to the normal level of 0.3%.

The customer’s production line recovered stable continuous stamping. This service fully reflected our company’s service philosophy of “treating the root cause rather than the surface symptom”. We not only solved the immediate quality crisis, but also helped customers establish standardized lubrication management rules, reduce die wear, cut scrap loss and lower long-term maintenance cost.

From the customer submitting the fault report to the completion of verification and resumption of formal production, the total service cycle was 11 hours. The customer’s production supervisor expressed recognition for our fast response, systematic diagnosis and practical training.

Q1: What production risks will uneven lubrication and nozzle blockage of double-side oil feeder bring to the 160T servo punch press stamping line? A1: Insufficient and uneven oil film will lead to increased friction between material and die edge, producing surface galling, scratches and over-limit burrs, directly raising the scrap rate and rework workload. Local dry friction will generate high temperature, accelerate carbide die wear and chipping, greatly shortening die service life. Dripping oil will form irregular oil stains on the strip, affecting subsequent welding, painting and surface treatment of finished parts. Long-term unstable lubrication will also cause inconsistent stamping force feedback, bringing hidden trouble to servo punch press stroke control accuracy.

Q2: Why will different brands of stamping oil mixed filling cause nozzle and filter blockage? A2: Different stamping oils use different base oil systems and additive packages such as anti-wear agent, antioxidant and rust inhibitor. After mixing, chemical incompatibility may occur, producing colloidal flocculent precipitate. The precipitate is sticky and easy to combine with iron powder and dust in the oil tank, forming oil sludge. The sludge will gradually block filter meshes and nozzle orifices. Even if the nozzle is cleaned, blockage will reappear quickly if deteriorated mixed oil is not replaced completely.

Q3: How should operators judge whether the oil feeder is abnormal during daily patrol? A3: Operators can check from four dimensions: first, observe the atomization state of each nozzle, confirm whether the mist is fine and uniform, and check for oil dripping or no oil output; second, check the flow and pressure data displayed on the HMI, compare with the standard value; third, observe the oil stain distribution on the strip surface, whether there are areas with no oil or excessive oil accumulation; fourth, check whether the oil tank liquid level is normal and whether the oil liquid turns dark and has peculiar smell. Once abnormal signals are found, stop adjusting pressure blindly and report to maintenance personnel.

Q4: What are the core highlights of our after-sales service in this lubrication system fault case? A4: We provide 24-hour remote pre-diagnosis within 15 minutes to guide customers to collect fault data and avoid misoperation; regional warehouse reserves complete filter, nozzle and sealing accessories to reduce waiting time; engineers adopt layered isolation diagnosis instead of blind replacement; after repair, professional maintenance training and maintenance checklist are delivered; multi-node follow-up is arranged after service to track long-term running stability. The whole service covers emergency repair, technical transfer and preventive management.

Q5: What is the recommended regular replacement cycle for the filter elements of double-side oil feeder? A5: Under normal working conditions, the suction filter inside the oil tank and the fine filter before the nozzle manifold are recommended to be inspected every month and replaced every 2 months. If the production material is thick plate with a large amount of iron powder, or the workshop dust is heavy, the replacement cycle should be shortened to 1 month. The replacement record needs to be filled in the equipment maintenance log.

Q6: Is higher atomization air pressure better for stamping lubrication? A6: No. Excessive air pressure will not increase the effective lubrication effect. On the contrary, high air pressure will blow stamping oil into large oil drops, causing splashing and dripping, wasting lubricating oil and polluting materials and workshop environment. Too low air pressure cannot form uniform mist, resulting in concentrated oil output. It is necessary to keep the air pressure within the range specified by the equipment manual.