Case Study: Blower Units for Rack Ovens and Wagon Ovens


Technology leader in in-store baking and bakery systems


  • Correct system imbalances in 12 circulation units
  • Assemble customer-provided components
  • Deliver complete fan units


  • Development of customer-specific toolings
  • Assembly of all components except motor
  • Deliver 700 units / year


  • Eliminated system failures caused by imbalances
  • Reduced variant complexity
  • Freed up customer’s production capacities
  • Reduced customer’s reclamation costs

Project Overview

Our customer has been using punker fan wheels for the blower units of their technologically leading bakery systems and shop baking stations since the 1960s/1970s. After the customer consulted us in 2013 regarding the imbalances occurring in the blower units used in rack ovens and wagon ovens, punker has since then been responsible for the assembly of 700 blower units p.a. and the procurement of the required motors for the customer. This way, the customer was able to reduce their complaint costs significantly.

Our Customer

Our customer is a manufacturer of bakery systems, in-store baking stations and automation technology. Technologically, their systems are among the most sophisticated systems on the market today. The company group has subsidiaries on four continents where they employ a total of 700 people.


The company has been purchasing backward-curved fan wheels of the HLS70 series from punker since the 1960s / 1970s. Later, forward curved wheels of the TS / Fprime range were also added. The wheels are used in blowers for the various ovens.

In 2013, imbalances in the blowers in the field increased, which led to complaints from their customers. Due to limited capacities on the part of our customer and punker’s many years of experience in the development of air technology solutions for the food industry, the customer consulted us and asked for an analysis of the units.


The customer provided punker with all components of the blowers for a comprehensive analysis of the units. After a sampling phase at punker, the imbalances could be eliminated. In order to relieve the customer’s capacities, the production of the motor plate, the procurement of the motors and the assembly of the blower units is now carried out at punker.

punker supplies the customer with 12 different blower types in a total quantity of 700 units p.a. Further units/types will follow. Since punker took over the production and assembly in 2015, there have been no more complaints due to imbalances, the purchase of the blower units is cost-neutral for the customer.

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Technical Questionnaire




    Your eMail address*:




    Attention: Frequently all operating details are either not known or only inaccurately known. You must therefore as a manufacturer make sure by suitable tests that the correct fan wheel has been selected. When the following questions are answered as comprehensive as possible, we can submit a proposal as quickly and as defi nite as possible. Please give us further details on a supplementary sheet. This questionnaire on no account replaces a technical specifi cation (TSP).

    1. General Information

    1.1. Fan application (type of unit and appliance, rail application, compressor, etc.)

    1.2. Are there any special requirements on safety conditions? (e.g. explosion protection, danger of accident at wheel failure, etc.)


    Please state special requirements:

    1.3. Medium to be handled and its state (e.g. smoke gas with t max = 300° C, dust laden air or similar)??

    2. Air Duty

    2.1. Volume flow
    V' = m³/hcfm

    2.2. Static pressure increase
    Δpfa = PainWG

    2.3. single flow/double flow?

    2.4. Density of the medium
    rho = kg/m³lb/ft³

    2.5. Max. media temperature
    t = °C°F

    2.6. Max. A-rated sound power level
    Lw = dB(A)

    2.7. Other technical details (e.g. max. flow speed, special curve steepness, etc.)?

    3. Drive

    3.1 Is the speed variable?


    minimum ; maximum rpm
    fixed speed rpm

    3.2. Direct motor drive

    n = rpm

    3.3. Is a maximum motor power specified?


    maximum motor power Pw = kWhp

    3.4 Operating mode?

    S1 - IEC 60034-1other operating mode

    other operating mode =

    4. Dimensions and Constructional Execution of the Fan Wheel

    4.1. Can a standard fan housing be used?


    max. dimensions of spiral housing:

    4.2. Are certain main wheel dimensions defined?

    main wheel dimensions:

    4.3. Hub bore
    Ø d = mm, fit
    with/without keyway?


    4.4. Hub model and arrangement (e.g. inside the wheel, outside, etc.)

    4.5. Material of wheel body


    other material:

    4.6. Additional surface protection


    other surface protection:

    4.7. Additional specifications

    5. Demand, Pricing

    5.1 You would like to request an offer for:

    Sample wheels: pcs.

    (later) batch: pcs/year

    Lot size pcs/order

    5.2 planned start of production TT/MM/JJJJ