Combining Theory with Practice for Win-Win Collaboration

Release Date:

10-05-28

Nanweike Company (Nanjing Iveco Automobile Co., Ltd. of SAIC Motor) has been a valued customer of our company for many years, during which our cooperative relationship has remained exceptionally harmonious. This is attributable not only to the high level of attention paid by our company’s leadership but also to the effective communication and mutual trust between our technical and quality departments. Since 2010, through statistical analysis of the monthly scrap material returned from Nanweike Company for Camshaft blanks, we have observed a steady monthly increase in the amount of scrap, with the lowest figure in the first quarter at 3.95% and the highest reaching 5.29% (since we supply raw blanks, defects such as sand holes, slag inclusions, and surface imperfections are unavoidable; Nanweike allows up to 4% scrap). Notably, in April the scrap rate soared to 10.27%. Witnessing piles of nearly finished blanks being returned, our company leaders and management were deeply concerned and promptly issued an order to identify the root cause of the problem and work with the customer to reduce scrap within a specified timeframe, directing our technical, quality, and sales departments to take immediate action. Upon receiving the directive, a task force dedicated to reducing scrap—comprising elite personnel from the technical, quality, and sales departments—was dispatched to Nanweike’s camshaft machining line the very next day. By collecting relevant on-site data and engaging in direct discussions with operators, the team quickly compiled preliminary information and data, which they immediately analyzed to determine the underlying causes. The analysis revealed that, due to the use of resin-bonded sand casting for the camshaft blanks, during the high-temperature pouring process and before the blank cools and solidifies, the resin-bonded sand breaks down under the heat, gradually losing support at the smaller end of the blank far from the gating system. As the blank cools and solidifies, gravitational forces cause slight downward bending, resulting in what appears to be a straight blank on the surface but actually exhibits a subtle curvature at the microscopic level (as shown in the figure above). During the 10th machining operation—milling the end face and drilling the center hole—the customer uses a standard steel pin to align and position the center hole, which represents the theoretical center point. In theory, this should pose no problem; however, since it does not coincide with the actual center of our blank, after machining the center hole, the machined center deviates from the blank’s true center in one particular direction. This misalignment leads to uneven material allowance in subsequent processes, causing turning and grinding operations to produce non-circular parts and ultimately resulting in scrap. To verify our findings, the task force conducted multiple on-site inspections at the customer’s facility. On-site verification by the customer confirmed the accuracy of our analysis, demonstrating that the only viable solution was to adjust the positioning datum so that it aligns as closely as possible with the blank’s inherent center. Given that the customer’s production line operates on a dedicated, specialized setup and is currently in peak season, any shutdown would be unacceptable. Therefore, if adjustments were to be made, they could only proceed with the approval of the customer’s technical and equipment departments. On April 27, the sales department coordinated with the customer’s technical, production, and equipment leaders, and the task force presented extensive data and evidence to persuade the customer. Without disrupting normal production, they took advantage of the customer’s lunch break and the time immediately following the day’s production tasks to carry out three temporary fine-tuning steps on-site, while simultaneously collecting and analyzing data post-adjustment to ensure the effectiveness of the changes. Over more than half a month of continuous on-site monitoring by our task force, it became evident that, following the adjustment of the 10th-process positioning datum, the customer’s scrap rate dropped significantly—from nearly 20 defective pieces per day in April (mostly due to non-circular turning and grinding)—to just 3–4 pieces per day now (primarily sub-surface sand holes, slag inclusions, and cold shuts, with daily input of 200 blanks). The customer’s camshaft workshop supervisor and shift foremen expressed considerable satisfaction. However, the full extent of the improvement will only become clear after one month of continued production following the adjustments—that is, by the end of May, when the exact scrap figures can be accurately assessed. After initially confirming the effectiveness of the adjustments, the task force decided to swiftly convert the customer’s temporary measures into permanent ones, thereby preventing a resurgence of scrap caused by instability in the shims used for adjustment. We designed and fabricated pressure blocks to replace the temporary shims and proactively visited the customer’s site to perform the replacement. The enthusiastic cooperation and positive attitude displayed by the customer’s on-site operators clearly demonstrated their satisfaction with the results of this adjustment. On May 25, Nanweike returned the May batch of blank machining scrap, which, upon counting, totaled 101 pieces (mainly sub-surface sand holes, slag inclusions, cold shuts, and surface defects). The customer had processed 3,400 blanks in May, resulting in a scrap rate of 2.97%; the average scrap rate for the first quarter was 4.45%, whereas prior to the adjustment, the April scrap rate stood at 380 pieces out of 3,700 blanks, equating to 10.27%. The tangible benefits are evident to all: in just one month, disregarding differences in the number of blanks processed, we directly reduced the customer’s scrap by 279 pieces. According to the customer’s internal calculations, each finished camshaft incurs labor costs of approximately RMB 300 per piece, along with tooling, cutting tools, and energy expenses totaling about RMB 150 per piece. Thus, the customer saved a total of 279 × RMB 450 = RMB 125,550. Moreover, they gained an additional 279 finished camshafts (market price: RMB 580 per piece). At the same time, our company also avoided producing 279 scrap blanks, saving RMB 279 × RMB 70.5 = RMB 19,669.5 in sales costs, truly achieving a win-win outcome. Through my involvement in this project, I have come to deeply appreciate that if we pay closer attention, think more carefully, and go the extra mile for our customers, we not only create value for them but also reap rewards for our own company—and most importantly, we earn their trust. Li Xiangguang

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