没有质量的机会

在金属加工过程层次结构中，磨削操作通常是工件上完成的最后一次或接近最后一次的加工。作为精确的部分，它可以在各种生产过程中（刷新，转动，热处理等）进行逐步添加到零件中。

Because grinding is at the end of the processing line, by the time the parts hit the grinding operation, they are close to their highest value. It’s no time to take chances by making assumptions about the quality of the previous operations.

For a speciality grinding shop like Asteroid Grinding Company (Des Plaines, Illinois), a policy of “trust but verify” has held it in good esteem with more than 200 customers for more than 30 years. Asteroid is a job shop’s job shop. Its work comes from other shops that rely on Asteroid’s grinding expertise.

CNC主管特里·马格努斯（Terry Magnus）说：“当您从其他商店中进行工程处理，必须添加最终的维度和表面饰面规格时，检查和测量变得与磨削本身一样至关重要。两者非常交织在一起。”

The Business In Brief

Asteroid is first and foremost a job shop. As such, process flexibility is among its most important assets for success.

The company was founded in 1966 as a centerless grinding shop offering throughfeed and infeed capabilities. About 5 years ago, it branched out into CNC OD/ID cylindrical grinding.

For the CNC side of the business, lot sizes typically run from ten to 5,000 pieces. Most of the cylindrical work that Asteroid processes requires two operations, front and back. Setup and teardown for a job change average between 1 and 2 hours total.

Matched pairs of grinders are arranged in a cell configuration to expedite the processing. Set one is performed on one machine and set two is performed on the second.

马格努斯先生说：“我们选择依次磨碎，因此在整个批次运行之前都可以抓住任何公差问题。三个单元格由两个操作员运行。”

Asteroid has 33 employees. The company grinds and polishes workpieces in a variety of materials including steel, stainless, aluminum, acrylic, copper, ceramic and brass. Size ranges from 0.060-inch diameter to 4 inches in diameter can be ground in the shop.

大多数进入小行星的工作都是预处理的。“我们不铣削或转弯，”马格努斯先生说。“当然，因为我们是最后一次触摸零件之前触及客户的人，所以有很大的压力要快速扭转工作。在这里，磨削的经验与测量和检查专业知识合并以帮助我们快速制作良好的部分。通常，我们在3天内转过订单。”

集成流程

对于像小行星这样的磨削商店，检查和测量对成功至关重要。这两个学科必须手戴手套以生产零件以打印规格。

“At every step in the process, we apply appropriate inspection levels to ensure a good grind,” says Mr. Magnus. “As a job shop, we must be as flexible in QC as we are in metalworking. Some customers’ jobs require 100 percent inspection; others may only need five parts per hour to make the specified CpK.”

小行星系统地接近其制造业。它认为操作员，研磨机和盖饰系统是必须在一致中运行的单个单元。这是一个相互依存的过程，需要操作员的技能正确有效地为给定的作业设置机床和量规。该机器必须能够持有所需的公差，并且量规必须确认该零件是按编程为编程并传达任何差异的。

“例如，在一份工作中，印刷品指定了一个0.005英寸的公差带，”马格努斯先生说。“我们整天在0.0002英寸内运行工作。该系统有效。”

Triple Check

小行星的测量和检查方案分为三个步骤：预处理，进程和后处理。由于在商店的CNC磨床上运行的大多数工作都来自另一家商店，因此可以检查开发的工作以确定尺寸和数量。此外，许多部分都经过热处理，因此此初始检查确定是否由于热处理而发生任何失真。

Once the quality and quantity of incoming parts is confirmed, routers and programs for the CNC machine are created and the job is scheduled. Setup of the machine follows, which includes wheel dressing, adjusting the centers and setting the in-process gages.

设置机器以运行批量，操作员测量了前五个部分。如果他们被认为是规格的，他们会去商店检查员，后者确认了操作员的测量。然后，这项工作准备好运行。

While the job runs, an hourly quota is pulled for inspection. Inspection varies depending on the customer’s SPC requirements and the complexity of the part. Asteroid inspects a minimum of one part per hour for its own internal statistical process control.

在配备Marposs Unimar量规的机器上，进行内部测量是自动化的。使用GAGE的自动尺寸功能，通过磨床的CNC补偿了车轮磨损，热量生长和零件量的变化。马格努斯先生说：“这种过程中的监视使操作员可以运行第二台机器或检查零件。”“因为量规会在机器上注册过故障或在过故障的情况下自动关闭机器，因此磨细胞可以在休息或午餐时运行。”

在运行结束时，研磨单元操作员将最终的零件移交给了检查部门，该部门对批处理进行了最终的随机检查。如果一切顺利，则该工作将释放。

好练习

Asteroid is successful because of its dedication to zero defect production. Using a combination of manual and automated gaging equipment, as well as redundant checking by the operator and inspection department, this shop has found an efficient balance between throughput and quality.

将测量和检查整合到加工过程中已增强，而不是阻碍小行星按时交付零件的能力。马格努斯先生说：“我们的系统的运作方式是在整个过程的一部分中发现并解决的，而不是在工作运行后找到整个不良零件的运行。”