GROUP 4
 Continuous and Batch Processes
 Multi-vari Chart
 Short Run Specification Chart
 Gage Control
Continuous and Batch Processes
Continuous Processes
Continuous processes in manufacturing are used to produce
very large quantities of product per year (millions to billions
of pounds).
Continuous Processes
Often, a physical system is represented through variables that
are smooth and uninterrupted in time. The control of the
water temperature in a heating jacket, for example, is an
example of continuous process control. Some important
continuous processes are the production of fuels, chemicals
and plastics.
Batch Processes
Batch processes are generally used to produce a relatively low
to intermediate quantity of product per year (a few pounds
to millions of pounds).
Batch Processes
Some applications require that specific quantities of raw
materials be combined in specific ways for particular
durations to produce an intermediate or end result. One
example is the production of adhesives and glues, which
normally require the mixing of raw materials in a heated
vessel for a period of time to form a quantity of end product.
Other important examples are the production of food,
beverages and medicine.
Group Control Chart
The group control chart plots multiple streams of
observations or attributes on the same chart. This simplifies
interpretation when monitoring many process streams or
characteristics. Process streams may be different machines,
assembly lines, operators, or the like. All of these may be
plotted on a single group chart.
Multi-Vari Chart
In quality control,
multi-vari charts are a visual
way of presenting variability
through a series of charts.
 Multi-vari charts were first described by
Leonard Seder in 1950, though they were
developed independently by multiple sources.
 They were inspired by the stock market
candlestick charts or open-high-low-close
charts.
 More recently, the term "multi-vari chart" has been used to
describe a visual way to display analysis of variance data.
 Analysis of variance (ANOVA) is used to test hypotheses about
differences between two or more means. the multi-vari chart is
only useful for comparing the variability among at most four
factors.
 It uses a vertical line to show the range of variation of the observed
values within a single piece or service.
Types of Variation in Multi-Vari Chart
1. Within a Unit
– length of vertical lines exceed half
of the specifications.
2. Unit to Unit
– excessive scatter.
3. Time to Time – appearance of non stationary
process.
1300
1400
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0800
0900
1000
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2100
2200
Examples of Multi-Vari Chart using ANOVA
Extra:Watch a video how to to this in excel...must have
a sound system
A candlestick chart is a
combination of a line-chart and a
bar-chart, in that each bar
represents the range of price
movement over a given time
interval. It is most often used
in technical analysis of equity and
currency price patterns.
Candlesticks are usually composed of the body (black or white), and
an upper and a lower shadow (wick): the area between the open and
the close is called the real body, price excursions above and below the
real body are called shadows. The wick illustrates the highest and
lowest traded prices of a security during the time interval
represented. The body illustrates the opening and closing trades. If
the security closed higher than it opened, the body is white or
unfilled, with the opening price at the bottom of the body and the
closing price at the top. If the security closed lower than it opened,
the body is black, with the opening price at the top and the closing
price at the bottom.
An open-high-low-close chart also OHLC chart, or
simply bar chart is a type of chart typically used to illustrate
movements in the price of a financial instrument over time.
Each vertical line on the chart shows the price range (the
highest and lowest prices) over one unit of time,
Tick marks project from each side of the line
indicating the opening price (e.g. for a daily bar
chart this would be the starting price for that day)
on the left, and the closing price for that time
period on the right. The bars may be shown in
different hues depending on whether prices rose
or fell in that period.
Short Run SPC
Short-Run SPC Chart
 SPC means statistical process control
 Used when either an organization produces a low volume of
outputs or the process itself only lasts for a short time
 Uses specification standards of the product to determine
whether or not a process is in control.
 Uses target values, not actual values.
 Target value is what the blueprint or design specifies the
product should be as far as weight, diameter, density or other
dimensions.
Specification chart
 Gives some measure of control and a method of quality
improvement.
 The central line and the control limits are established using
the specifications.
Using the formula:
Cp = USL – LSL / 6σ
σ = USL – LSL /6Cp
Assuming…
 Specifications call for 25.00 0.12 mm
 Central line X0 = 25.00
 Difference between USL and LSL is .24 mm
 Cp = 1.00
 So, σ is .04
Interpretations:
 If Cp = 1.00, plotted points will form a normal curve within
the limits.
 If Cp > 1.00, plotted lines will be compact about the central
line.
 If Cp < 1.00, plotted point falls outside the limits. It could be
due to an assignable cause or due to the process not being
capable.
Gage Control
Group 4
DFM
Basic Definitions
 Gage(Gauge)
 a dimension (eg. thickness of a product)
 any device used to obtain measurements
 Control
 Management process in which the (1) actual performance is
compared with planned performance, (2) difference between
the two is measured, (3) causes contributing to the difference
are identified, and (4) corrective action is taken to eliminate or
minimize the difference.
Gage Control
 SPC requires accurate and precise data; however, all data have
measurement errors:
Observed Value = True Value + Measurement
Error
Gage Control
 Measurement variation is divided into repeatability, due to
equipment variation, and reproducibility, which is due to
appraiser(inspector) variation.
 It is called GR&R or gage repeatability and reproducibility.
Gage Control
 Before we perform calculations to evaluate GR&R, the gage
is calibrated first.
 Calibration is performed either in-house or by an
independent laboratory.
 It is accomplished so that it is traceable to reference
standards of known accuracy and stability, such as those of
the National Institute for Standards and Technology
Gage Control
 Introducing of formulas/equations and sample problem still
need to be inquired from teacher
Gage Control
 Although the order of taking measurements is random, the
calculations are performed by part and appraiser.
 The analysis will estimate the variation and percent of
process variartion for the total measurement system and its
component’s repeatability, reproducibility, and part-to-part
variation.
Gage Control
 If repeatability is large compared to reproducibility, the
reasons may be that:
1.
2.
3.
4.
The gage needs maintenance.
The gage should be redesigned to be more rigid.
The clamping or location for gaging needs to be improved.
There is excessive within-part variation.
Gage Control
 If reprodcibility is large comparred to repeatability, the
reasons may be that:
1.
2.
3.
The operator needs to be better trained in how to use and
read the gage.
Calibrations on the gage are not legible.
A fixture may be needed to help the operator use the gage
consistently.
Gage Control
 Guidelines for acceptance of GR&R:
Under 10% error
10% to 30% error
Over 30% error
Gage system is satisfactory.
May be acceptable based on
importance of application,
cost of gage, cost of repairs,
etc.
Gage system is not satisfactry.
Identify the causes and take corrective action.