Posts Tagged ‘CAD training’

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Using Goal Seek to aid in model design

Thursday, July 19th, 2012

The Goal Seek command is one of the calculation tools available for engineering problem solving. It is available in the 3D environments and while drawing 2D geometry in a 2D Model sheet, a drawing sheet, a profile, or a sketch.

The Goal Seek command automates engineering calculations, which can be based on dimensioned geometry, to achieve a specific design goal. Goal seeking finds a specific value for a dependent variable (dependent by formula, for example) by adjusting the value of another variable, until it returns the result you want. Goal seeking shows you the effect on the geometry and it will also update the Variable Table with the new value.

The following is just one example of how to use the Goal Seek command to aid in model creation. This example illustrates how to use the Goal Seek command to help design a sheet metal cover.

Note:  For this example, we have to create a hole pattern, on the top of the cover, to allow for air flow. From previous analysis it’s been determined that we need a minimum open area of 6000 mm². To achieve this we will start by creating a circular cutout and rectangular pattern.

I first create and position a 10 mm radius circle, as shown below, to create our initial cutout.

While still in the sketch environment, I select the Area command, from the Inspect tab > Evaluate group.

I then click in the area of the circle.

I accept the Area by selecting the green checkmark on the command bar.

Next I open the Variable table and locate the Area variable and rename it to Cutout_Area.

 

I also locate the 10 mm variable for the circle radius and rename it to Cutout_Rad.

I then close the Variable table and complete the cutout using the Through All extent option.

Next I create a Rectangular Pattern, as shown below, using the Fit option with the following values:

  • X: = 10
  • Y: = 5
  • Width: = 170 mm
  • Height: = 65 mm

 

The completed pattern should look like the image below.

To prepare to use Goal Seeking I need to create some User Variables. First, I find the X and Y occurrence variables and rename them to X_count and Y_count.

Next I create a Total_Area variable by clicking in an empty row and selecting the area type, from the pull down scroll, as shown below.

I then type in the name Total_Area and tab over to the Formula column. In the Formula column enter the following formula:

                      Cutout_Area*(X_count*Y_count)

 

Note:  I have now created a variable to calculate the total open area created by the pattern. I can now use this variable to help adjust the cutout radius to obtain the desired area of 6000 mm².

To do this I select Goal Seek from the Inspect tab > Evaluate group.

The Goal Seek command bar will appear.

I select the Goal Variable, which is the Total_Area.

I then select the variable that I will allow to change to obtain the Goal variable, which is the Cutout_Rad.

Now I enter in my target value of 6000 mm². (I just have to enter in 6000)

Note:  Goal Seek will now run through a series of iterations, where it will adjust the cutout radius, until it obtains the target value. When it is complete, it will show you the finished model, and post the number of iterations it used and the total elapsed time it took, in the bottom on the Status bar.

If I open the Variable table and view the User Variables, I can see that the radius of the cutout is changed from 10 mm to 12.36 mm, and our total area is now 6000 mm².

Using the Goal Seek command allowed me to determine the optimal radius for my holes without having to do any advanced calculations.

For more practice, try the Solid Edge tutorial on ‘Using Engineering Calculation Tools in Solid Edge.

Using the mouse to manipulate the model view in Solid Edge

Thursday, June 21st, 2012

The middle mouse button, or scroll wheel, provides improved model rotation in ST4. You can now select a vertex, edge, or face as the model rotation center. To do this, simply following the steps below:

First you must let the system know that you want to enter the rotation mode. This is achieved by a single click to the middle mouse button (MMB), on an empty space. You will notice the cursor changes appearance. Before you click the MMB your cursor looks like this:

                    

After you click the MMB you cursor will look like this:

  

Notice that the little blue face, indicating selection mode, has disappeared.

You now have three options available to you: 

 

1. Rotate using a position on a face.

  •  - You can now move the cursor over the face shown below. Notice the dark pink dot, indicating that you are in the rotate mode.

 

  • - If you now hold the MMB down, the part will rotate about the dark pink dot. In other words, the dark pink dot becomes your center of rotation.

 

2. Rotate using a position on an edge.

  • - You can move the cursor over any edge. Notice the entire edge highlights.

 

  • - Holding the MMB down allows you to rotate about the edge. In other words, the edge becomes the axis of rotation.

 

3. Rotate using a position on a vertex.

  • - You can move the cursor over any circular edge. Notice the entire edge highlights.

 

  • - Holding the MMB down to rotate allows you to rotate about the vertex of the circular edge. In other words, the vertex of the circular edge becomes the axis of rotation.

 

Note:  Once you have completed the rotation, you are returned to selection mode. You will have to single click to the middle mouse button (MMB), on an empty space, if you wish to perform another controlled rotation.

 

Other handy mouse controls in Solid Edge

 - Pan the view. Press the Shift key while you drag the MMB to pan the view.

 

- Zoom. Scroll the mouse wheel to zoom in and out.

 

Note: The setting for this scroll behavior is found in Solid Edge options_Helpers page. Enable Value Changes Using the Mouse Wheel. If this option is on, the mouse wheel changes the value in a value edit field. Use Ctrl+mouse wheel to zoom in or out.

- Zoom Area. Press the Alt key while you drag the MMB to zoom into an area.

- Double–click the MMB: Fits the view.

 

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Simplifying the placement of certain dimensions in Draft

Tuesday, April 17th, 2012

Recently I had a customer contact our support line, looking for an easier way to place some dimensions. He was self taught on Solid Edge and was attempting to place the following dimensions on a formed tube.

 

 He had figured out how to do this by creating and using extra sketches, but felt there should be an easier way to achieve his desired results. I walked him through the process, and felt that this would be a good tech tip to share.

To place the 2 dimension shown, do the following:

1. On the Sketching tab, in the IntelliSketch group, make sure that the intersection option is toggled on.

 

2. From the Home tab, in the Dimension group, select the Distance Between command.

 

  •  
    • - Make sure your option is set to Horizontal/Vertical on the command bar.

 

  •  
    • - Move the cursor over the bottom centerline so it highlights. DO NOT CLICK

 

  •  
    • - Now move the cursor over the angled centerline and hit the ‘I key’ on your keyboard. (I is for intersection)

 

  •  
    •  - Then move the cursor over to the vertical centerline and click.

 

  •  
    • - place the dimension.

 

Note: Hitting the ‘I key’, tells the system to find and select the intersection point between the 2 highlighted lines. If more than one intersection point is possible, a list window will appear allowing you to select the desired intersection point.

3. From the Home tab, in the Dimension group, select the Angle Between command.

 

  •  
    • - Make sure your option is set to Horizontal/Vertical on the command bar.

 

  •  
    • - Select the horizontal centerline at a non-keypoint.

 

  •  
    •  - Select the vertical centerline at a non-keypoint.

 

  •  
    • - Place the dimension.

 

Note: the trick here is to not select the lines at keypoints (endpoints or midpoints).

There are several hot keys and various command options, which assist in placing dimensions in sketches and draft files. Take the time to review the help section on each dimension command and you will save yourself a lot of time and frustration.

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How to add an attribute column to a BOM in NX

Tuesday, April 3rd, 2012

In the part attribute, I’ve created the Plist attribute, make sure you have the object selection set to “apply to component as part attribute” if you want to save the information in the part, otherwise use the “apply to occurrence in the assembly”.

In the part list I’ve created a new column and did a RMB on the full highlight column

Select Style and go to the column tab.

Click on the arrow.

Select Plist from list and OK twice.

Is Training Worth It? – Calculate your Return On Investment

Tuesday, March 27th, 2012

In today’s competitive market, businesses are looking to get the most out of their employees, systems, software and machines. With the ever changing technology, this can be somewhat challenging.  Too often companies will invest in new technology but not invest in the training on the new technology. The most common reasons for this are:

  • - I don’t have the time to take the training.
  • - I can’t afford the cost of the training.
  • - I can train myself for free.
  • - I train one employee and he/she can train the rest.
  • - I have a high staff turn over and it’s not worth training them.

As a trainer I have heard all these excuses and more. They all essentially evolve around cost. Therefore, it is important that companies look at both the ROI of professional training and the cost of not taking professional training.

How to calculate the ROI of professional training

To calculate the ROI, you need to determine the total cost of the training course and compare it to the total financial benefit derived from the course. The cost of the course can be determined as shown below:

Cost of course                   = $ 2000

Salary of employee           =  $1000

Travel & Living Expenses  = $1000

Total cost of course           = $4000

The financial benefit derived from the course can be a little harder to determine and often depends on the individual. Below is a one potential example;

Suppose John Smith attends a course on a CAM software package. In this course he learns new and faster methods to create programs. Assuming a modest 10% increase in his program generation skills, we can start calculating the financial benefit. If John makes $25 per hour and he works 50 weeks a year week, allowing 2 weeks for vacation, the company pays him $50,000. If he works 10% faster the company’s immediate savings is 50,000 x 0.10 = $5000. We can also assume that John’s programs will be more efficient, saving machine time, cutter wear, and possibly less manual finishing work. His improved knowledge may also lead to fewer errors in the programs, resulting in less scrap. You may also want to consider any extra profits obtained by the increase efficiency. In other words John will be able to produce 10% more work from which the company will profit. So in John’s example we can calculate the financial benefit as follows:

Estimated savings from improved output                     = $ 5000

Estimated savings from downstream operations         = $ 2000

Estimated savings from reduced rework and scrap   = $ 1000

Estimated additional profit from improved efficiency    = $ 2500

Total financial benefit                                  = $ 10500

Using the following formula to calculate the ROI,

Net gain (total benefit-total costs) = ____ X 100 =____
  total costs  

we get an ROI of 162.5. Clearly this would justify John taking the course, especially when you consider that the financial benefit estimates are very conservative.

You can also view this from another direction. What is the company’s cost if an employee doesn’t take professional training?

Cost of not taking training

Let’s assume that you hire a new designer. This designer has CAD experience but does not know your CAD system. You hand him\her a manual or some tutorials and have him\her learn the system on their own. From the previous example we can assume that you are saving $4000 dollars in training. But how much are you really saving?

Although estimates vary on the topic of study, many agree that 1 hour of professional training could be equal to as many as 16 hours of teaching yourself. In other words you could spend up to 2 days reading, experimenting and learning a process that a professional trainer could teach you in 1 hour. If we extend this model we have one week of professional training = 16 weeks of self teaching. The cost to the company at $25 per hour is:

640 hours (16 weeks) x $25  =  $16,000

You also have to factor in the lost time in production for 15 of those 16 weeks that the new designer is not producing because the are still trying to learn the software. Any mistakes made through this process will also have a ripple effect throughout the company, costing more time and money. You also have to consider lost production time from any experienced employees who may be mentoring the new employee. If the experienced employee spends an average of 20% of his time helping the new employee you will lose one full week of man hours in every 5 weeks.

So for a conservative estimate, let’s assume that a new employee can learn the CAD package in 10 weeks with some assistance from experienced employees. Each week the new employee improves his/her output by 10% per week. The cost to the company can be calculated as follows:

Cost of no productive work over 10 weeks is:

  New Employee Experienced Employee
Week 1 1000 200
Week 2 900 200
Week 3 800 200
Week 4 700 200
Week 5 600 200
Week 6 500 200
Week 7 400 200
Week 8 300 200
Week 9 200 200
Week 10 100 200

Total cost of lost production  =     5500  +  2000 

                                                  =     7500 

Remember you still have to factor in the cost of fixing any training errors and the downstream effect of each error. If we assume a modest 5 errors, at an average cost of $500 per error, this results in:

Total cost of lost production = 10,000

Keep in mind that the cost could be much higher depending on the new employee’s ability to teach him/her self, and how many errors are made in the process.

Finally, you’ll have to wonder if the self taught employee has learnt the most efficient use of the software. With today’s software there are often several methods to achieve the same desired results. Each method has advantages and disadvantages depending on downstream factors. Too often self taught individuals find one method to solve a problem and use it, without further investigation to see if a more efficient way exists.  A good professional trainer will teach the different methods highlighting the situations where each method is most efficient.

Other excuses

Some companies have chosen to train one employee and have him/her train the others. They look at this as a cost savings to the company. Although this may appear to save you money you have to factor in the cost of using the first employee as your trainer. Every time he/she is training other employees, he/she is not producing work. Plus the assumption is being made that this employee has learned and retained the same knowledge as the professional trainer. This is often a false assumption, leaving the company paying almost a similar cost for a lower standard of training.

I’ve saved my favorite excuse for last. Some companies will not pay for professional training because they have too high of a staff turn around. It has been proven time and again that stress levels rise in adults when they have to learn something new. If you combine the stress for self teaching with the daily stress of the workplace, you may be contributing to the staff turn around. By providing professional training in a setting designed for learning, the employee will learn, without the work stress, and return to work with the proper skills.

Conclusion

When you actually take the time to do an honest, realistic cost analysis, it quickly becomes clear that sending your employees for professional training is a good investment.  The above examples are very conservative, yet they clearly show the advantage to professionally training your staff. Although it may be difficult to free up time and money to provide professional training, the cost of not doing so will be greater in the long term.

A well-trained employee is more likely to be satisfied with the company he\she works for, which in many cases means he\she will be less likely to leave to find a job elsewhere.  The payback is not just in a few months or a year. Instead, it can be a lifetime of service and reduced operating costs.

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Non-graphic parts in Solid Edge assemblies

Friday, March 9th, 2012

Assemblies often contain components for which there is no model required, such as paint, grease, oil, labels, and so forth. These non-graphic parts still need to be documented in the parts list and bill of materials that are created for the assembly. In Solid Edge, you can use the File Properties command on the Application menu in the Part and Sheet Metal environments to add custom properties to an empty part document. These custom properties allow you to define the required information for these types of parts. You can create two types of non-graphic parts: parts that require a unit type and quantity, and parts without a unit type and quantity.

 Types of non-graphic parts

Parts with a unit type and quantity

Some non-graphic parts require a unit type and quantity. For example, you may require four liters of oil in an engine assembly. You can create a part document named OIL.PAR, and then set the unit type, Liters, in the part document. Later, when you place the oil.par document in the assembly, you can set the unit quantity using the Occurrence Properties command on the Edit menu.

Parts without a unit type or quantity

Other non-graphic parts require no unit type or quantity. For example, you may require a small quantity of grease between certain parts in the assembly. These types of part quantities are usually documented “As Required” on a parts list or bill of materials. For these types of parts, you define the custom properties and the text string you want in the part document. You do not have to edit the occurrence properties in the assembly.

 Placing Non-Graphic Parts

Since non-graphic parts do not need to be positioned with assembly relationships, you can place the part in the assembly by holding the SHIFT key, and drag the part into the assembly.

 

Create a non-graphic part that uses units and value

This procedure shows you how to define custom properties for a non-graphic part that requires units, and a value for those units. Although no 3D model is required for these parts, they still need to be documented in a bill of materials or parts list. For example, you may require 4 liters of oil in an assembly.

Step 1. In the part document, choose Application menu→Properties→File Properties to open the Properties dialog box.
Step 2. On the Custom tab, in the Name box, type: SE_ASSEMBLY_QUANTITY_OVERRIDE.
Step 3. In the Type box, select Number from the list.
Step 4. In the Value box, type 0 (zero). Then click the Add button.                                                                                                                                 
Step 5. In the Name box, type: SE_ASSEMBLY_QUANTITY_STRING.
Step 6. In the Type box, select Text from the list.
Step 7. In the Value box, type the unit and number of decimal places you want. For example, Liters;4. Then click the Add button.           

Note:  You must separate the unit type and decimal places with a semi-colon (;). If the number of decimal places you want is 2, you do not need to enter a value for the decimal places.

To use the custom properties in an assembly, do the following:

Step 1. Place the part in the assembly.
Step 2. Select the part in the PathFinder tab or the graphics window, then on the shortcut menu, choose Occurrence Properties.
Step 3. On the Occurrence Properties dialog box, type the quantity value in the Quantity cell for the occurrence. Notice that the unit value you specified in the part document is displayed in the User-Defined Quantity column.

Tip:

  • - You can place a non-graphic part in an assembly without applying relationships by holding the SHIFT key, then dragging the part into the assembly.
  • - You can also set the quantity value using the Occurrence Properties button on the Place Part command bar.
  • - If you use many non-graphic parts at your company, you can create a template that has the non-graphic part custom properties defined.

 

Create a non-graphic part that is unit less

This procedure shows you how to define custom properties for a non-graphic part that does not require units. Although no 3D model is required for these parts, they still need to be documented in a bill of material or parts list. For example, you may require a small quantity of grease that on the parts list is documented “As Required”.

Step 1. In the part document, choose Application menu→Properties→File Properties to open the Properties dialog box.
Step 2. On the Custom tab, in the Name box, type: SE_ASSEMBLY_QUANTITY_OVERRIDE.
Step 3. In the Type box, select Number from the list.
Step 4. In the Value box, type 1 (one). Then click the Add button.                 
Step 5. In the Name box, type: SE_ASSEMBLY_QUANTITY_STRING.
Step 6. In the Type box, select Text from the list.
Step 7. In the Value box, type the constant text you want. For example: As Required. Then click the Add button.                                                       

 

To use the custom properties in an assembly, do the following:

  • - Place the part into the assembly. The “As Required” property is automatically recognized in the Occurrence Properties dialog box. To review the part’s properties, select the part in the PathFinder tab or the graphics window, then on the shortcut menu, choose Occurrence Properties.

Tip:

  • - You can place a non-graphic part in an assembly without applying relationships by holding the Shift key, then dragging the part into the assembly.
  • - If you use many non-graphic parts at your company, you can create a template that has the non-graphic part custom properties defined.

 

Set part properties in an assembly

  1.  Click a part or subassembly in the assembly.
  2.  Right-click, then choose Occurrence Properties on the shortcut menu.
  3.  In the Occurrence Properties dialog box, set the options you want to use.

 Tip:

  • - You can also set the part properties with the Occurrence Properties command on the shortcut menu when a part or subassembly is selected.
  • - When you select the top level assembly entry in PathFinder, then click the Occurrence Properties command, the entire assembly structure is displayed in a bill of materials format. You can use the (+) and (-) symbols to expand and collapse the assembly structure.
  • - When you select one or more parts or subassemblies, the selected occurrences are displayed in a table format that cannot be expanded or collapsed.
  • - If you need to change the properties of a subassembly, you must first check out all subassemblies where the occurrence properties are being modified. Then the documents can be saved and checked back in to Teamcenter.

*Text passages taken from Solid Edge Help files.

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