Integrated Design Models like Spreadsheets

Easier than using a spreadsheet. Write linked equations for user defined variables. Use a Quick Entry sheet for specified input variables with question prompts. Calculate cost drivers such as quantity, cycletime, takeoff factors, tooling life, number of cavities, machine cost, rental rates, scrap rates, etc. The result is complex cost models with inter-related tasks for which you enter a few values such as part dimensions and get detailed cost estimates.  

• Description
• How to Build a Cost Model

Description

Note: Each task can have it's own design model called a task model. Variables in the task model can be linked to the design model.

The design model solves explicit (the unknown variable is only on the left hand side) equations sequentially. Solved variable values are substituted in unsolved equations until all equations are solved. This is similar to solving expressions for each cell in a spreadsheet. Standard mathematical functions can be used in the equations.

 Using this application the user can build a library of design models for product sizing, quantity estimation, structural design, parametric costing, etc. These can then be linked to the cost analysis module to generate cycletimes, material quantities, tooling costs, scrap rates, and other cost factors. The result is powerful cost models that can be used to conduct sensitivity analyses as a function of design variable values. For example, the user may define the dimensions, volume, weight, scrap rate, tooling costs, molding machine cost, mold cycletime, etc. for a thermoplastic part. By linking these variables to a cost model, one can change part dimensions and immediately see the effect on part cost, line loading, etc.

 The design module is also used to drive laminate analysis. The design model can be linked to a laminate and used to define laminate loads. For example, a beam equation can also be written to define a laminate load such as Nxx. Results returned by the laminate analysis can be used to predict structural response. For example, elastic moduli returned by the laminate module can be used in a beam deflection equation. The user can modify laminates and readily see the effect on deflection and stresses that are defined by the beam equations.  

Some useful functions that can be used in equations include:

MachineTime: Calculates machining time given cutting speed, diameter and length of cut. You can also specify materials and allow the function to calculate cutting time.

Mix & Layup: Use to calcuate material properties of mixtures (density, cost/unit weight) and laminate properties (resin, filler quantities, laminate cost, etc).

LCAverageTime: This "Learning Curve" function computes cumulative average time for learning curves. It can be used to define task cycletimes in the cost model as a function of volume.

Sum: Sums a series expression with a user defined index variable that can be included in the expression to be summed.

 Dsum: Double sums a series expression with two user defined index variables that are included in the expression to be summed.

Interp: Does linear or quadratic interpolation given three pairs of x and y coordinates. Use it to model tooling costs as a function of size, etc.

FunctionRoot: Finds the root of a user defined function in one variable. The function itself can contain variables that are solved in other design equations.

A typical example is solving a cubic equation such as x3+x+offset using the expression:

 FunctionRoot('x^3+x+
                        offset-10','x',-1,10,1E-6)

The value for 'Offset' will be substituted during solution.
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