In the over-broken and effectively broken ranges, as the ratio increases, the radius of the chip also increases. However, in the region where tangled chips are produced the trend reverses itself. In this region, the chip radius decreases as the ratio increases. The results regarding the chip radius are interesting, but they do not provide much useful information for the machine operator who needs to know where to place a chip breaker to effectively control chips in a turning operation. In order to make the graph useful for this purpose, it has been broken down into three distinct regions by two vertical dashed line. The first line is located at the point where the ratio of breaker location to feed equals 13.5. To the left of this line the chips are over-broken. The second line is located at the point where the ratio is 29.5. To the right of this line the chips are all underbroken. Between these lines lies the region where effective breakage was noted. The transitions from one type of chip to another are very distinct. This indicates that the ratio of breaker location to feed is a good measure for predicting and adjusting breaker location for proper chip control when turning 4150 steel. Conclusions The data collected for this investigation indicates that it is possible to provide a practical means for a machine operator to predict where an obstruction type chip breaker should be placed for effective chip control when working with 4150 steel. The location of the breaker can be calculated using a ratio of breaker location to the feed which results in well-broken chips. Since the feed will have been set and is known to the operator, the proper breaker location can be calculated by multiplying the feed by the proper ratio. A good value of this ratio appears to be about 20, so for effective chip breaking with 4150 steel, the breaker should be located back from the primary cutting edge by a distance 20 times the feed. The beauty of this method is that the main cutting parameters need not be changed to get good chips. This means chip control is possible without decreasing the efficiency of the process significantly. These experimental results also agree with the analysis in the sense that the ratio of the feed to the location of the chip breaker is indeed the most important parameter. The optimal ratio of chip breaker location to feed may also depend on other parameters such as tool geometry and materials as these variables affect the cutting process. However, for a given tool geometry and materials, properly broken chips can be obtained over various machining conditions by maintaining the ratio at a constant value
