When it's time to Stepup your machining

In this article, we are going to look at a small feature in Mastercam 2020 Opti Rough toolpath that we have found at MECAD Manufacturing can have a significant impact on reducing your machine time.

When doing any machining job, the goals are usually to gain the best result in the least amount of time. To do that we usually look at the factors that can influence the time for a machining operation. These factors are, but are not limited to, the power of your machine, what tools you are using, the stock material, and the machining strategy being used. Changing these can either increase or reduce the machining time on a part.

In most cases, changing your machine, tooling or stock material is not always an option, but if we could improve the way that the tool moves, we can keep the before mentioned unchanged and still reduce your cycle time.

When machining a part, the finishing operation is something we don’t want to mess with, as this might have a certain surface finish to get the green light. This leaves us with the roughing operation, and it is here where we could use a small feature in Mastercam 2020’s Opti Rough to dramatically reduce the cycle time.

To explain this further let’s look at an example:

Here we have the top part of a flashlight with a stock size of 85 x 210 x 30 mm.

Let’s assume that we have already done a facing operation and with the roughing, we would like to achieve 2.5mm steps. Next, we are going to perform an Opti Rough toolpath on this part using a 10 mm flat endmill running at 4000 RPM and a feed of 500 mm/min with a 25% (diameter of the tool) stepover as well as a 25% stepover. Verifying the toolpath, we get the following stock model with a cycle time of 2 hours and 6 min.

Now, one way to reduce the cycle time by only making changes to the toolpath would be to change to the stepover and stepdown. But how can we do this without losing our desired 2.5mm steps?

This is where the Stepup function in the Mastercam’s OptiRough comes in. To explain this let’s make the following changes. Let’s drop down in the stepdown to 100% of tool diameter (10mm)  giving us a full flute cut and backing up with the stepover to 10% (1mm), but let’s add a stepup of 25% (2.5mm) to still get that desired steps on the rough cut. 

After we have regenerated the toolpath, this is the stock model we get with a cycle time of 1 hour and 50 min.

The results look pretty much the same with a reduction in the cycle time of 16 minutes! To understand how stepup work let’s look at the two toolpaths from the right view.

Stepover: 2.5mm; Stepdown: 2.5mm; No Stepup; Cycle time: 2h 6ma

Stepover: 1mm; Stepdown: 10mm; Stepup: 2.5mm; Cycle time: 1h 50m

As you can see from the pictures above, with stepup on there are a lot less toolpaths line (Blue line) on the outer edges of the part, but the same close to the walls of the part. What’s happening is that with stepup on Mastercam will take the full flute cut up to where it can and would then come back and do a stepup cut to give us the 2.5mm steps.

I would encourage you to try Stepup in your Mastercam programs and see how this will help you to reduce your machining time.

Keeping your eyes out for more article or contact us at MECAD Manufacturing to see how you can reduce your machining time even further using the toolpath in Mastercam 2020.