This month’s Tool of the Month is on the more advanced side of the user spectrum. Based on its cost and complexity alone, the average home builder probably won’t be looking to purchase their own profilometer. However, for anyone who owns a honing machine, you should probably pay attention, as this is definitely something that should be in your toolbox.
“Anyone that is concerned about getting their cylinder finishes correctly should be looking at a profilometer,” says Keith Jones, Total Seal’s Director of Technical Sales. We’ve discussed a number of different theories, methodologies, and practices regarding determining what the optimal surface finish is in previous articles (such as this one). However, regardless of what type of finish you think is optimal for a given engine combination, you need to know that you actually have the finish you think you do.
While there are million-dollar machines that allow you to program your desired finish, that will actively measure and monitor all of the variables as it hones each cylinder, which probably isn’t within the realm of reality for most shops. However, a handheld profilometer, while expensive, is a much more attainable tool for any engine professional operating on anything but the most shoestring of budgets.
What is a Profilometer
First, we need to explain what exactly a profilometer is and what it measures. Essentially, a profilometer measures the roughness of a surface. While there are a multitude of different types of profilometers and methods of measurement, for this article we’ll focus on the most common — the mechanical method. In that method, the profilometer physically drags a stylus across the surface being measured and uses the vertical and horizontal movement to create values and a graph of your cylinder wall’s actual finish.
A profilometer will calculate a number of different measurements. For what we are doing (measuring engine cylinder walls) there are four measurements set up by Total Seal out of the box: Average Roughness (Ra), Core Roughness (Rk), Reduced Peak Height (Rpk), and Reduced Valley Depth (Rvk). Those are a mixture of physically obtained data (stylus measurements) and calculations within the unit itself, based on that data.
The cylinder’s finish is critical to the performance of the engine. As the cylinder wall retains the oil film the piston rings ride on during the combustion process, it’s of the utmost importance that you have the correct finish for your combination. For what you want each of those measurements to be, we’ll refer you to the previously linked article, or one of Total Seal’s awesome videos, ranging from quick explanations to in-depth seminars, diving deep into the theory behind your target measurements, and how to achieve them.
Total Seal’s Mitutoyo Profilometer
Profilometers have been around for ages, but the unit offered by Total Seal is an incredibly advanced tool that has taken modern measuring to the next level. Today’s modern profilometers offer more bang for the buck than those of even 20 to 30 years ago,” says Jones. “They have a much greater range of data available, more processing power. They sample more data points, offer more scales of data, and have the ability to download and save data to a computer.”
Moving on to the specific model of profilometer that is the subject of this article, the Mitutoyo Surftest SJ-210 Series 178 Portable Surface Roughness Tester (what a mouthful) is a JIS-, VDA-, ISO-1997-, and ANSI-compliant instrument. This particular model has been chosen by Total Seal for both its level of accuracy and precision, as well as for its feature set. As it is a highly configurable tool, Total Seal offers it pre-configured for use, with the standard drive unit and a remote tether to the display unit. “We calibrate and set it up for measuring cylinder surfaces,” Jones explains. “The end-user simply takes it out of the box, connects it, and it’s ready to go.”
The Mitutoyo’s display unit has a 2.4-inch color LCD display which offers a wealth of data and immense customization, from setting visual “out of spec” results, which can help in batch-run production-style situations, or even just ensuring all of the cylinders are within a given specification. Alone, the unit can hold 10 different sets of measurement configurations which can be expanded to 500 with the optional memory card, along with 10,000 measurement profiles.
Additionally, the unit has a USB interface, along with multiple other specific outputs, allowing you to download measurement data to a PC for further analysis (or just so you can view the data on a larger screen) and storage. This can be a helpful way of maintaining job records, in case questions arise down the road. If you happen to be in a situation where you feel your honing data needs to be protected, the SJ-210 is password-protectable, to keep your data secure.
If you happen to be worried about the complexity of the tool, don’t be. “It is easy to use. The challenge is changing your honing processes to achieve the desired end result,” Jones explains. “Finding a new honing process is not difficult, but will take some practice and maybe a different stone selection than what they already own. Most shops have the stones they need, it’s just a matter of changing the ‘habits’ they have in the process from rough to finish cylinders. And we will help walk them through this as best we can.”
Learning to use a new tool, especially one this advanced, can be intimidating. The end result is not only better performance for your engines in the long run, but with all the extra features Mitutoyo has packed into their profilometer, better record-keeping and data tracking abilities as well. Add in the support from Total Seal to get you up and running, and having your own profilometer looks better and better. At the end of the day, if you aren’t actually measuring your cylinder finish, you’re just guessing.
If you’re interested in learning more about the theory of cylinder wall finishes beyond just measuring them, videos like this from Total Seal’s YouTube page are definitely worth the time investment.