BTS DE PRODUCTIQUE MÉCANIQUE

Session 1995

Epreuve écrite d'anglais


TOOL MONITORING: IS IT RIGHT FOR YOU?
Robert Spee, Senior Marketing Engineer, Montronix Inc, USA.

1        [In-process tool condition monitoring was first introduced in the early 1980s and is gaining acceptance as a necessary component of modern machining equipment by many manufacturers. 

2        Tool condition monitors provide rapid detection of tool and process failures such as collisions, tool breakage and tool wear. By detecting failures as they occur, manufacturers are able to improve the quality of their products while realising valuable savings.

3        Tool monitoring enables greater automation and faster, more aggressive machining. If tool monitoring is so great, shouldn't every manufacturer fit each machine in the plant with the latest tool monitoring technology? Not necessarily. Whether or not one can benefit from tool monitoring depends on the particular manufacturing process. This article will discuss how to calculate the potential benefits of tool monitoring and describe the type of manufacturers who can benefit from this technology (and the type who can't).] 

4        Detecting collisions immediately can prevent serious damage to the workpiece, tool and machine. Broken tools, if not detected, can lead to collisions. Tool monitoring can detect broken tools immediately and minimise damage. Tool inserts are often replaced at fixed intervals. Since normal insert life varies from 10 % to 50 %, fixed intervals must usually be set at the low end of the tool life curve. 

5        With this policy, inserts are often replaced well before they are 100 % worn. Detecting wear with tool monitoring allows tools to be replaced only when they are worn to a desired level, decreasing the cost of tools and the downtime associated with frequent tool changes. Depending on the application, tool monitoring may provide 
savings in
* Tool cost 
* Tool holder and fixture cost 
* Scrap and rework 
* Direct labour
* Machine downtime 
* Productivity  

6        In some cases, potential benefits may be measured not only in terms of direct savings, but also in terms of the advanced machining technology that can be safely and effectively employed when combined with tool monitoring, as in the following example. 

High Volume Automation

7        A volume producer of cast iron parts doubled productivity through the use of sialon ceramic inserts that allowed for a 200 % increase in feedrate. While ceramic inserts can cut at very high speeds, they are more brittle than carbide inserts. 

8        Tool monitoring ensures the safe use of higher speed machines and more brittle tool materials by reducing the risk of damage to machine and parts from tool breakage and other tool or process failures. Table 1 shows the performance improvements made with the addition of a Montronix TS200W tool monitoring system. Running eight-hour shifts, 750 shifts per year, this manufacturer was able to produce 126,000 additional parts per year. 

9        In addition to productivity improvements, direct cost savings were achieved with tool monitoring by increasing tool usage, reducing tool holder damage and reducing machine downtime. For example, prior to tool monitoring, the manufacturer replaced tool inserts every 25 parts. With tool monitoring, the average parts per insert was increased to 37, reducing the cost of inserts and the downtime to change the tools. Tool monitoring allows high volume manufacturers to achieve more aggressive machining rates while protecting the often higher cost machines used to achieve higher levels of automation. 

10      While tool monitoring almost always provides benefits and insights into the machining process, some manufacturers may not see sufficient benefits to economically justify tool monitoring for their operation. Tool monitoring is often not suitable for manufacturers who meet most or all of the following criteria: 
1. Small lot sizes
2. Low-cost machines 
3. Low-cost parts 
4. Continuously supervised 
5. Non-aggressive conditions
 

11      A job shop manually producing small lots of non-critical aluminium parts, for example, probably could not cost justify tool monitoring.

TABLE 1 

Parameter                    Before tool monitoring      After tool monitoring

Speed                            300 m/min                          900 m/min

Feedrate                         0.5 mm/rev                         0.8 mm/rev

Material removal rate      375cm3/min                        1.800 cm3/min

Insert                              Carbide                              Sialon Ceramic

Cycle time                     102 sec                              45 sec

Pieces per hour             24                                      45

European Machining
May-June 1993


TRAVAIL À EFFECTUER 

1/ Traduire en français depuis « In-process tool condition monitoring » jusqu'à « and the type who can't. »  (8 points) 

2/ Questions : 

a/ In your own words explain what tool monitoring consists in. (50 mots environ) (4 points) 

b/ Your manager asks your written advice as a technician about the desirability of adopting a tool monitoring system or not. (150 mots environ) (8 points)

Corrigé de la traduction

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