Product pricinpal
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Project aims
We were assigned with the topic of “Horizontal Milling Attachment”. In this project we are expected to design a horizontal milling attachment which can be used on the vertical milling machines.
Horizontal Milling Machines
2000px-Milling_machine_diagram.svg.png文字方塊: 1.	Base  2.	Column  3.	Knee  4.	Working Platform  5.	Working Platform  6.	Overarm  7.	Arbor
A horizontal mill has the working table (also as known as working platform). The table can move in x, y and z axis so that the milling machines can perform a three dimensional cutting. The cutters are mounted on a horizontal arbor across the table. The arbor is fixed into the spindle which provides a horizontal rotation. A majority of horizontal mills also feature a ±15 degree rotary table that allows milling at shallow angles.
We can use end mills and the other types of tools available to a vertical mill in a horizontal milling, but the real advantage of using horizontal milling machines lies in arbor-mounted cutters, which is also as known as side and face mills.  They have a cross section like a circular saw, but are generally wider and smaller in diameter.
side-face-milling-cutter.jpg
Since the cutters are well supported by the arbor, quite heavy cuts can be performed. Therefore rapid material removal is possible. These make the horizontal milling useful for milling grooves and slots. Another advantage of using horizontal milling is that several cutters may be mounted together on the arbor for milling a more complex shape of slots and planes at the same time.

hor mill.jpgSpecial cutters can also cut grooves, bevels, radii, or indeed any section we desired. These specialty cutters are usually very expensive and not used in general purposes. So the simple side and face mills are more preferable when carrying out general milling. Simple mills have one spindle while duplex mills have two. Cutting gears is also easier to be performed in horizontal milling.
vert_mill.PNG

  1. Table lock bar
  2. Saddle automatic moving bar
  3. Saddle automatic moving control dial
  4. Saddle manual wheel
  5. Knee manual wheel
  6. Quick button
 
  1. Cutter
  2. Spindle
  3. Spindle head
  4. Column
  5. Table
  6. Saddle
  7. Knee
  8. Base
  9. Spindle switch
  10. Spindle speed gear lever
  11. Spindle speed control lever
  12. Oil tank
  13. Table manual wheel
 Vertical Milling Machines
In the vertical mill the spindle axis is vertically oriented. Milling cutters are held in the spindle and rotate on its axis. The spindle can generally be extended and the position of the table can be adjusted, both will give the same effect. The vertical mill allows plunge cuts and drilling.
Vertical mills can further be classified into two subcategories: the bedmill and the turret mill. Turret mills, like the ubiquitous Bridgeport, are usually smaller than bedmills and are considered by some to be more versatile. In a turret mill the spindle remains stationary during cutting operations and the table is moved both perpendicular to and parallel to the spindle axis to accomplish cutting. In the bedmill, the table moves only perpendicular to the spindle's axis, while the spindle itself moves parallel to its own axis.
Work in which the spindle's axial movement is normal to one plane, with an endmill as the cutter, lends itself to a vertical mill, where the operator can stand before the machine and have easy access to the cutting action by looking down upon it. Therefore most diesinking work has always favored a vertical mill. The heavier the work piece, the more likely one is to want it to sit directly on the table rather than being mounted indirectly on an angle plate (or rotary table or indexing head perpendicular to the table), just as short, heavy work pieces are easier to set up on a vertical lathe or boring mill than on the headstock of a horizontal-axis lathe. Even in the CNC era, a heavy work piece needing machining on multiple sides lends itself to a horizontal machining center, while diesinking lends itself to a vertical one.
Reasons for designing HMA
Given the general preference and wide acceptance on vertical milling machines than the horizontal milling machines, users do not tend to buy horizontal milling machines. But it is undeniable that the horizontal milling has its own advantages over vertical milling, as we mentioned before in the previous parts, therefore the horizontal milling attachment (HMA) was introduced.

The working principle of the HMA will be discussed later, but the reasons why our group was assigned the topic will be discussed now.

Our Industrial Center does not have horizontal milling machines, in order to carry out horizontal milling for teaching and manufacturing purpose, the industrial center has purchased a HMA in the market. Although this HMA is way cheaper than the horizontal milling machines, it still costs about $40,000 HKD. Having considered the cost of manufacturing and difficulty in designing, our supervisor decided to design and manufacture a HMA for another model of vertical milling machines by ourselves. (There are different models of vertical milling machines available in our machining workshop). By completing the project, we can reduce the cost from $40,000 HKD to $2,000 HKD.
Working Principle of HMA

Existing Horizontal Milling Attachment (HMA) in our machining workshop

 big.jpg
The working principle of the Horizontal Milling Attachment is quite simple. The attachment is simply attached on a vertical milling machine. The attachment will convert the vertical spindle rotation into the horizontal movement of cutter, having the same effects as horizontal milling. The detailed design of the HMA will be introduced in the designing part.