---
title: "Add a shift, buy a machine or recover lost hours?"
description: "Recover lost hours first, add a shift when you can staff it and buy a machine when you can’t. Each route priced per good part on one CNC lathe, by hand."
category: "Operations and lean"
author: "Ulises Carrasco"
published: "2024-11-25"
updated: "2026-10-20"
source_url: "https://www.iotflows.com/blog/add-a-shift-or-buy-a-machine/"
---
> Question: Should I add a second shift or invest in another machine?

## Key takeaways

- Size a capacity gap in hours of planned production time at measured OEE before you price any option.
- Recovered hours inside existing shifts are the cheapest capacity, and every later shift or machine inherits the higher OEE.
- Overtime pays time and a half on wages and suits a small, temporary gap, not a lasting one.
- A second machine that needs its own operator carries the same wages as a second shift, so capital and staffing decide between them.
- Buy the machine when you can’t staff more hours, one operator can tend two machines, or demand outgrows the calendar.

Add a second shift when the machine is your constraint, you can staff the hours and its measured availability already sits near what that machine type can reach. Buy another machine when you can’t staff more hours or demand outgrows the calendar. Before either, measure how much of its scheduled time the machine actually runs: recovered hours are the cheapest capacity, and every later shift or machine inherits them.

The worked example below sizes a capacity gap in hours, prices four ways to close it on one CNC lathe, and ends with a decision guide. It’s for owners and plant managers who want the arithmetic before they sign a purchase order or post a job ad.

## Four ways to add capacity

Every option adds good parts in one of two ways. It adds hours, or it makes more good parts in the hours you already pay for. The second way raises *OEE* (overall equipment effectiveness): availability × performance × quality, the share of planned time that turns into good parts at the ideal rate.

| Option | What changes | What you pay for |
|---|---|---|
| Recover lost hours | OEE inside existing shifts | Engineering time, small tooling |
| Overtime | Longer weeks for the same crew | Time and a half on wages |
| Add a shift | Planned hours on the same machine | Wages, differential, supervision |
| Buy a machine | Machines on the same shifts | Capital, install, floor, an operator |

> **Definition.** **Capacity gap** is the difference between the good parts demand calls for in a period and the good parts the current schedule makes at measured OEE, expressed in hours of planned production time at that OEE.

> **Definition.** **Recovered hours** are hours of planned production time that a machine already has on the schedule but loses to stops, slow cycles or scrap, and that it gets back as good output once those losses shrink.

Measured hours come first because every option is priced against them. A plant that guesses its machines run 85% of the shift prices a new machine against hours that don’t exist.

## Size the gap in hours first

Good parts per week follow from three numbers: the hours you schedule, the ideal rate and OEE. Turn the formula around to get the hours a demand needs.

**Good parts per week** = Planned production hours × Ideal rate × OEE

**Hours needed** = (Demand in good parts) ÷ (Ideal rate × OEE)

The [OEE calculation](/blog/how-to-calculate-oee/) explains each factor. The example below uses one machine throughout the article.

#### Worked example: One CNC lathe on one shift

- Shift: 8.5 hours on site with an unpaid 30-minute lunch, 5 days, so planned production time is 40 hours a week.
- Ideal cycle time: 2.4 minutes, so the ideal rate is 25 parts an hour and 1,000 parts a week.
- Measured: availability 50%, performance 90%, quality 96%, so OEE is 0.50 × 0.90 × 0.96 = 43.2%.
- Today: 1,000 × 0.432 = 432 good parts a week, or 10.8 good parts an hour.
- A new order lifts demand to 648 good parts a week, 216 more than today.

Hours needed at today’s OEE: 648 ÷ 10.8 = 60 hours.

**Result:** The gap is 20 hours a week of planned production time at 43.2% OEE

The operator loads and unloads every part, so the job needs a person at the machine for every hour it runs. That detail decides the labor cost of every option below.

The same lathe shows why the calendar matters. *TEEP* (total effective equipment performance) is OEE multiplied by utilization, where utilization is planned production time over all time.[1] One 40-hour shift fills 40 ÷ 168 = 23.8% of the week, so TEEP here is 0.432 × 0.238 = 10.3%.

The other 128 hours exist; the question is which ones you can buy cheapest. The [TEEP guide](/blog/utilization-uptime-oee-teep/) works the shift-pattern arithmetic in full.

## Recover lost hours first

A machine that looks busy all shift can run far less than that. On a semi-automatic CNC, where an operator loads and unloads each part, measured uptime (availability) lands between 50 and 70%, and a goal of 60 to 75% is reasonable, as the [utilization ranges by machine type](/blog/utilization-goals-by-machine-type/#cnc) explain.

The [CNC expectations table](/docs/production/cnc-machines/#expectations) gives the ranges for manual, semi-automatic and automatic machines. The lathe in the example sits at the bottom of its range, so it has hours to give back.

Recovered hours come from three places:

- **Changeovers.** Move setup work outside the stop and standardize it, see [how to measure changeover time](/blog/measure-changeover-time/).
- **The top stop reasons.** Rank stopped time by reason and fix the first two bars, see [the downtime Pareto](/blog/downtime-pareto/).
- **Short stops.** Pauses of a minute or two add up across a shift and hide inside performance, see [micro-stops](/blog/micro-stops/).

Breaks add hours rather than recover them. A relief operator who covers the 30-minute lunch keeps the machine cutting, which adds 2.5 planned hours a week on this shift for the cost of the relief operator’s time.

#### Worked example: Raise availability on the same lathe from 50% to 62.5%

- New OEE: 0.625 × 0.90 × 0.96 = 54.0%, or 13.5 good parts an hour.
- One shift now makes 40 × 13.5 = 540 good parts, 108 more than today.
- Hours needed for 648 good parts: 648 ÷ 13.5 = 48 hours.
- The improvement work (a setup cart, preset tools and an engineer’s time) costs $6,000 once in this example.

**Result:** Recovery adds 108 of the 216 parts; the other 108 take 8 hours a week at 54% OEE, down from 20

Figure: Good parts a week on one lathe: 432 today, 540 after raising availability to 62.5%, 648 with recovery plus 8 overtime hours or with 20 overtime hours alone, and 864 with a second shift or a second machine. Demand is 648.

*Each route to a 648-part weekly demand on one CNC lathe, at today’s 43.2% OEE unless marked. Sample data.*

> **Count only recovery you have measured**
>
> An estimate of lost time is not a plan. Put a number on the recovered hours from a month of measured stops before you subtract them from the gap, or the order arrives and the hours don’t.

## What overtime, a shift and a machine cost

Price each option per week, with the same assumptions for all four. Wages come from BLS; the differential, overhead and machine price are example values to replace with your own. Material, tooling and power cost the same per part on any route, so they drop out.

- **Wage:** $30 an hour. Production and nonsupervisory workers in manufacturing averaged $30.21 an hour in September 2026 (preliminary).[2]
- **Loaded cost:** 1.5 times wage, or $45 an hour. Manufacturing employers paid $48.62 an hour in total compensation against $32.50 in wages in June 2026, a ratio of 1.50.[3] BLS measures these costs per hour worked.[4]
- **Overtime:** time and one-half on the regular rate for hours over 40 in a workweek, for covered nonexempt employees.[5] That is $45 in wages per overtime hour. Per-person benefits such as health insurance don’t grow with the extra hours, and this example leaves payroll taxes out.
- **Shift differential:** $2 an hour. The FLSA requires no extra pay for night work; it is a matter of agreement between employer and employee.[6] Use your own rate.
- **Second-shift overhead:** $300 a week as this machine’s share of a supervisor, maintenance cover and lighting for the added hours.
- **Machine:** $180,000 installed, spread over 10 years of 50 working weeks, or $360 a week before financing.

### Overtime

Twenty overtime hours cost 20 × $45 = $900 a week, and the operator works 60 hours. In US workers followed from 1987 to 2000, jobs with overtime schedules carried a 61% higher injury hazard rate than jobs without, and 60 or more hours a week a 23% higher rate.[7]

Use overtime as a bridge while you recover hours or hire, not as the plan for a lasting order.

### A second shift

A second operator on the lathe from 4:30 PM costs 40 × ($45 + $2) + $300 = $2,180 a week. The shift adds 40 planned hours and 432 good parts at today’s OEE, twice what this order needs, so half of it waits for the next order.

### A second machine

A second lathe on the day shift needs its own operator, because this job keeps a person at the machine for every cycle. It costs 40 × $45 + $360 = $2,160 a week and also adds 432 good parts.

It also brings its own empty calendar: 128 unscheduled hours a week on a machine you now own. Price that before you sign, see [the cost of idle machines](/blog/cost-of-idle-machines/).

The labor term is what moves this result. If a bar feeder lets one operator tend both lathes, the second machine costs about $360 a week plus the time to load bar stock. That is the price of 8 overtime hours, for 432 more good parts.

## Compare the options side by side

Put the four routes side by side, all closing the same 216-part gap. Each cost per part divides the weekly cost by those 216 parts.

#### Worked example: Four ways to make 648 good parts a week

- Overtime only: $900 a week, or 900 ÷ 216 = $4.17 per added good part.
- Recover, then 8 overtime hours: 8 × $45 = $360 a week, or $1.67 per added part, plus $6,000 once.
- Second shift: $2,180 a week, or $10.09 per added part, with 216 parts of spare capacity.
- Second machine with an operator: $2,160 a week, or $10.00 per added part, with 216 parts of spare capacity.

Recovery saves $900 − $360 = $540 a week against overtime alone, so the $6,000 pays back in 6,000 ÷ 540 = 11.1 weeks.

**Result:** Recover first: $360 a week and an 11.1-week payback beat every other route for this order

Figure: Weekly cost to reach 648 good parts: $360 for recovery plus 8 overtime hours (with $6,000 once), $900 for 20 overtime hours, $2,160 for a second machine with an operator and $2,180 for a second shift.

*Weekly cost of each route to the same 648 good parts; the shift and the machine also buy 216 spare parts. Sample data.*

The answer changes when demand reaches twice today’s output. At 864 good parts a week, overtime alone would need 864 ÷ 10.8 = 80 hours, and recovery plus overtime would need 64-hour weeks.

A second shift and a second machine both make 1,080 good parts at the recovered 54% OEE, so both cover the order. Their weekly costs differ by $20, so the choice turns on staffing, capital and how long the demand lasts.

| | Recover hours | Overtime | Second shift | Second machine |
|---|---|---|---|---|
| Good parts added here | 108 | 216 | 432 | 432 |
| Weekly cost here | None | $900 | $2,180 | $2,160 |
| One-time cost here | $6,000 | None | Hiring and training | $180,000 |
| Needs new hires | No | No | Yes | Yes, unless tended |
| Ends with the order | Gain stays | Yes | Yes | No |
| Lifts later options | Yes | No | No | No |

One CNC lathe, one 40-hour shift, demand of 648 good parts a week. Sample data.

## Why measured availability changes the answer

The input that moves every hour above is availability, and it’s the one input a plant can’t read off the routing. Hold performance at 90% and quality at 96%, change only availability, and the hours needed for 648 good parts move by 20.

| Availability | Good parts an hour | Hours for 648 | Fits one shift |
|---|---|---|---|
| 50% | 10.8 | 60.0 | No |
| 62.5% | 13.5 | 48.0 | No |
| 70% | 15.12 | 42.9 | No |
| 75% | 16.2 | 40.0 | Yes |

Ideal rate 25 parts an hour, performance 90%, quality 96%, 40 planned hours a week. Sample data.

A planner who assumes 75% sees an order that fits one shift. The measured 50% says it needs 60 hours. Either number leads to a confident decision, and only one of them matches what the floor produces.

The same arithmetic catches a common mistake. A second machine run the same way as the first inherits the same losses, so it adds 432 good parts, not the 540 the first machine could reach. Fix the losses on one machine and both shifts or both machines carry the gain.

Measured [utilization](/docs/get-started/glossary/#utilization) depends on the denominator you choose. The [machine utilization guide](/blog/what-is-machine-utilization/) works through four of them. Use the one that matches planned production time here.

## Measure the hours before you decide

IoTFlows puts a SenseAi sensor on each machine. It reads vibration and sound from the outside and decides running or stopped every second, with no PLC connection.

The Advanced Report gives each machine’s utilization over a month or a quarter. Its **Shifts** filter counts only the hours inside the shifts you tick, so you can [set the period and filters](/docs/monitoring/advanced-report/#filters) to compare a day shift with a trial second shift.

Storm Power Components doubled machine utilization, met growing demand with its existing equipment and now schedules on real utilization data. Read the [Storm Power story](/customers/storm-power-components/).

[Production Scheduler](/platform/production-scheduler/) plans jobs on the same machines the sensors monitor, so a schedule uses the real part count.

## Choose shift, machine or recovery

Work through the options in this order. Each one is cheaper to try and easier to undo than the next.

Recover lost hours first when:

- measured availability sits below the range for that machine type;
- a few stop reasons or changeovers hold most of the stopped time;
- the order starts more than a few weeks out, so the fixes have time to land.

Use overtime when:

- the gap is a few hours per person per week;
- the order is temporary, or it bridges the weeks until a hire starts.

Add a shift when:

- the machine is your constraint and its availability sits near the top of its range;
- you can hire and train operators for the added hours;
- the demand looks lasting but not certain, since a shift can be dropped.

Buy a machine when:

- you can’t staff more hours;
- one operator can tend two machines, so the labor term disappears;
- demand exceeds what a full calendar makes at the recovered OEE;
- one machine is a single point of failure for a product line.

> **Not sure the demand will last?**
>
> Choose the shift. It costs about the same per week as a machine in this example, and you can end it when the order ends. A machine stays on the books for its full life whether the order repeats or not.

Before you sign either, run this check:

1. Measure a month of availability, performance and quality on the machine.
2. Compute the gap in hours at measured OEE, not at the rate on the routing.
3. Subtract only the recovery you have measured from the gap.
4. Price the remaining hours four ways with your own wage, differential and machine quote.
5. Plan the order on measured run rates, see [production scheduling on real run rates](/blog/production-scheduling-on-real-run-rates/).

## Questions

### Is overtime cheaper than hiring for a second shift?

Per hour the two land close. Overtime pays time and a half on wages, while a new hire costs wages plus benefits, about 1.5 times wages in manufacturing. Overtime adds no shift differential and no extra supervision, so it wins for a small gap that lasts a few weeks. It loses once hours per person climb toward 60 a week, where reported injury rates rise.

### Does a second machine need a second operator?

Only when the job needs a person at the machine for every cycle. A lathe with a bar feeder or a mill with a pallet changer can keep cutting while one operator tends two machines, and then the new machine adds its ownership cost and little labor. Time one full cycle and count the minutes the operator is busy before you price the purchase.

### How much should utilization rise before I buy a machine?

Compare measured uptime with the range for that machine type, not with 100%. A semi-automatic CNC, where an operator loads and unloads every part, runs 50 to 70% uptime, so a machine at 50% has hours to recover and one at 70% has few. Buy when the machine sits near the top of its range and the gap remains.

### Should I add a third shift or a weekend crew instead?

Run the same arithmetic. A third shift or a weekend crew adds planned production time on machines you already own, so it carries wages, any differential your agreement sets and the overhead of covering those hours, but no capital. Check how long it takes you to fill a night or weekend opening before you count on those hours in a quote.

## Sources

1. [TEEP: Calculate Total Effective Equipment Performance](https://www.oee.com/teep/), Vorne Industries (OEE.com), accessed Oct 16, 2026
2. [Industries at a Glance: Manufacturing, NAICS 31-33](https://www.bls.gov/iag/tgs/iag31-33.htm), US Bureau of Labor Statistics, accessed Oct 16, 2026
3. [Employer Costs for Employee Compensation, Table 4: private industry workers by occupational and industry group](https://www.bls.gov/news.release/ecec.t04.htm), US Bureau of Labor Statistics, accessed Oct 16, 2026
4. [Employer Costs for Employee Compensation, June 2026 (news release)](https://www.bls.gov/news.release/ecec.nr0.htm), US Bureau of Labor Statistics, accessed Oct 16, 2026
5. [Overtime Pay](https://www.dol.gov/agencies/whd/overtime), US Department of Labor, Wage and Hour Division, accessed Oct 16, 2026
6. [Night Work and Shift Work](https://www.dol.gov/general/topic/workhours/nightwork), US Department of Labor, accessed Oct 16, 2026
7. [The impact of overtime and long work hours on occupational injuries and illnesses: new evidence from the United States (Dembe et al., 2005)](https://doi.org/10.1136/oem.2004.016667), Occupational and Environmental Medicine 62(9):588–597, accessed Oct 16, 2026