By Paul Strefling

CNC Machining Tutorial for Ricor Cooling Manifolds.

T R A C E G A S S A M P L E I N T R O D U C T I O N S Y S T E M F O R E C E 4 8 0

A challenge of the TGSIS cooling system is the machining of the miniature stainless steel manifolds for the Ricor cooling fingers. The 2 sides of the manifold are smaller than a quarter dollar and require a significant amount of machining with a 1/32" end mill to obtain the correct path length for the gas sample. The two piece manifold can be seen in Figure 1 and 2.

Figure 1. The top of the Manifold. Notice the two 1/16" ports for the gas sample.

Figure 2. The bottom of manifold. The spiral is 1/32" wide.
Notice the two holes that match up to the top side.

This tutorial will explain the setup, procedure and finishing for machining of the cooling manifold on a generic CNC programmed with G-Code. This tutorial will also include the necessary G-Code to cut the manifolds.

Materials
The material chosen for the cooling manifolds was Super Corrosion-Resistant Stainless Steel Type 316, it has excellent corrosion resistance, good machineability and good weldability. From McMaster-Carr the product number is 8936K211, this is a 1” diameter 12” long precision ground rod.
Blank Preparation
A single blank can be used for both sides of the manifold. Depending on your vice size a blank of 2” allows for an easy and safe chucking. The blank should have both sides well faced on a lathe with a single side finished up with a 1000 grit polish for the bottom side of the manifold. It is essential that there are no dishing effects from the polishing; a planer surface is a must.

Chucking Up
For both cases, the blank needs to be placed in the vice standing on end. Angle blocks are recommended to achieve a proper clamping force. The polished surface is for the bottom of the manifold while the faced surface is for the top.

Axis Zeroing
The origin of the X and Y Axis are at the center of the cylinder. A simple dial indicator is used to find the center of the blank. The precision ground stock makes this a bit less tedious. The Z axis is .2000” above the top surface of the blank.

Tooling
The listed tooling in Table 1 is for both sides of the manifold.

Table 1

G Code

The included tarball, G-Code_Cooling_Manifolds.tar contains 3 files, these three files are all that is needed to perform the milling. Table 2 includes the details of each file, the respected tooling, and the spindle speed and feed rate. A newer mill with a faster spindle speed will be able to obtain a much higher feed rate.

Table 2. Details of the G Code Programs

Port Holes

The port holes were decided to be peck drilled by hand, but they could easily be automated, the following table lists the coordinates. If a 1/16” ream is available it would be a wise decision to ream the holes.

Table 3. Coordinates of the Port Holes

Finishing Notes

After the CNC machining is complete the parts can parted on the lathe. The top of the manifold is recommended to be parted at .075” while the bottom is recommended to be parted at .050”. After parting is complete the top manifold’s face needs to be polished with 1000 grit. After an acetone wash the manifolds are ready to be clocked and then welded. To clock the manifolds it isrecommended to place 1/16” ground rod in the port holes to line up with the holes in the bottom manifold.