Moving Beyond Tribal Knowledge

How rethinking your machine utilization strategy can yield outstanding results

By Curtis Rellick

February 1, 2010

Tribal knowledge is any unwritten information not commonly known by others within a company. This term is used most when referencing information others might need to know in order to produce quality products or services.

By nature, tribal knowledge contributes to an “our way of doing things” mentality, one that creates resistance to change or outside knowledge. Such closed thinking is a death knell to a manufacturing company when competitors or entire industries are stressing continuous waste-cutting and productivity improvement in response to ever-growing customer demands.

Productivity improvement is all around us. For instance, we’re seeing multiaxis and multifunction machine tools and simultaneous machining with both static and rotating tools of identical design.

Manufacturers are cutting at higher speeds on more rigid, accurate, and flexible machines, using advanced cutting tool materials and controls that allow innovative part processing. They are using programming functions for tool management, gauging, and in-process tool sensing. They have adopted modular workholding devices; in-process and postprocess gauging for workpieces and cutting tools with feedback for tool compensation; and tool condition sensors, along with tool identification and management software that interfaces with gauging, storage, tool kitting, and production software.

Yet these are not technology breakthroughs that will displace traditional machining methods for lathes, machining centers, and transfer lines. Outstanding results can be derived by using the technology we have on hand effectively. This also requires going beyond tribal knowledge and establishing standardized, open processes that can be used by all. What’s needed is a new strategy for improving machine utilization.

Beyond Cutting Alone

Process improvement is more than faster spindles or multifunction machines. It begins with understanding the three functional areas of the manufacturing process; inventory planning and control, preproduction planning and setup, and in-process manufacturing.

Producing smaller lots more often can slash inventory carrying costs and eliminate shelf-life problems like rust, contamination, and deterioration. Instead of producing one 8,000-unit lot of goods to deplete over a four-month period, a cost-effective approach is to produce four lots of 2,000 units at one-month intervals. Reducing the average inventory from 4,000 to 1,000 units cuts carrying costs by 75 percent and reduces shelf-life problems.

However, achieving these savings means increasing setup time 300 percent. Conventional tooling systems, setup procedures, and production planning are about 20 percent efficient today. With 60 percent of available machine time traditionally used for setups, and idle and stop time absorbing 10 percent each, only 20 percent remains for cutting. To improve machine and operator efficiencies and minimize machine downtime during tool and part changes, we need to eliminate that 60 percent bite into machine time.

The following products and services can provide a significant cost saving when they are part of a machine utilization strategy:

1. Quick-change tooling – Reduces downtime through the reduction of tool change and setup time.
2. Advanced cutting tool materials – Allows your cutting tools to run faster and longer between tool changes.
3. Tool kitting – Provides all the tooling necessary (including fixturing) to complete a production run or shift of operation.
4. Pregauged tooling – Eliminates time spent measuring cuts during the setup process; reduces the risk of human error at the machine control; and provides a quick and efficient method for changing worn tools.
5. Cutting tool management – Design a system for managing tools that is equally effective in controlling other types of inventory and consumable goods.

Such a manufacturing strategy transfers tool maintenance from the machine tool to the toolroom, thereby improving tool maintenance, increasing machine uptime and productivity, and decreasing nonconforming percentages.

Tool Kitting, Pregauged Tooling, and Preproduction Maintenance

The objective of tool kitting is to eliminate time spent searching for tools and performing on-machine tool maintenance. It pulls together all tools required to complete a production run or shift of operation and places them in a tool taxi near the machine. When tool change is necessary, the process is quick and efficient, permitting more machine run time and increasing productivity.

Once all necessary tools are fitted with new cutting edges and assembled in the tool taxi, the “F” and “L1” dimensions should be measured and recorded for each tool. This data will be used later for making offset adjustments following tool changes.

Additionally, all tool maintenance is performed in advance of the production run to avoid catastrophic tool failure and in-process tool maintenance. The objective of pregauging and preproduction tool maintenance is to eliminate lost production time caused by insert and insert pocket cleaning, on-machine tool maintenance, cut measurement, manual test cuts, gauging, computations, and offset adjustments.

Quick-change Tooling Comparison

Given an improved level of preparation, quick-change tooling can improve productivity.

Given this improved level of preparation, quick-change tooling can push productivity gains even farther. Quick-change tooling consists of two basic components: the clamping unit and the cutting head.

The clamping unit mounts to the machine tool and is the receptacle for the interchangeable cutting unit. When a tool change is necessary, an operator simply releases the locking system, replaces the cutting unit, and locks it into position. Machine downtime is a matter of seconds.

Consider the following example: Assume that the machine has been set up, the first part has been checked, adjustments have been made and the production run is in progress. The tool condition sensor has detected that the finish turn tool (station #8) shows signs of wear and it has a +/- 0.003-in. tolerance to hold on the part.

A common tool-change sequence is as follows:

1. Loosen clamp to change insert.
2. Clean insert pocket.
3. Clean insert and remove buildup.
4. Perform tool maintenance.
5. Index insert and tighten clamp.
6. Close door.
7. Make offset corrections to set cutting tool a minimum of 0.006 in. away from finish diameter.
8. Run test cut.
9. Open door.
10. Gauge part.
11. Compute math to determine part deviation.
12. Make offset adjustment within the machine tool control for the correct tool number and offset.
13. Close door.
14. Resume production run, or return to step 10 for final offset adjustment.
15. Complete part and gauge for accuracy.
16. Resume production run if part is acceptable, or return to step 10 if further corrections are required.

Using quick-change and pregauged tooling can reduce the steps in this operation to:

1. Change quick-change tool.
2. Make offset correction from pregauged data.
3. Close door.
4. Resume production run and place the used tool in the tool caddy. It will then be returned to the tool crib, where maintenance, pregauging, and tooling for the next production run can be accomplished.

Such a process change reduces an 8-minute tool-change sequence to 30 seconds, or saving 7.5 minutes per tool change multiplied by the number of tool changes per year. This can easily gain hundreds of hours of additional run time per CNC lathe or machining center.

Advanced cutting tool materials and integrated tool management systems are also important components of an effective machine utilization strategy, and certainly information abounds on such products and systems for interested manufacturing companies.

It is very important to realize, though, that effectively improving production is not a quick-fix, one-time process. It is both resource- and time-intensive for you and your technology partners. It will involve input and commitment from departments outside of production and engineering, such as inventory, purchasing, and IT.

For those willing to commence such a journey, though, many benefits await. Tribal knowledge, or “the way we’ve always done it,” is no longer enough to succeed in your business.

For more information, visit www.kennametal.com.